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I have recently discovered the term 'lightworker'.

Noun. "A person driven and motivated to do work which makes the world
a better place, improves people's lives, and/or elevates people to a
higher level of consciousness." (Wiktionary)

Wanting to learn more about the origin or religion associated with the word, likewise more about what a lightworker does or is; I have learned:

Lightworker's entry had been deleted from wikipedia

Whereas, it still has an entry in thespiritwiki

Is anyone able to provide me with more insight?

I am led to believe there is no concrete historical evidence in support of ‘lightworker’. If this is the case, I wonder if anyone would confirm this is why it had been removed.

Josh's answer correctly identifies lightworker as a term that has gained currency in fields of what outsiders (like me) might vaguely term "new age spiritualism."

The earliest match for the term lightworker that a Google Books search discloses is from Patricia Cota-Robles, The Next Step (1989) [combined snippets]:

As a Lightworker, I have come to set right the vibratory action of all energy and substance in my world and in all the world. As a Lightworker, "I AM" the Sacred HAND OF GOD, moving through this world, instantly re-establishing Divinity wherever this Sacred Fire is applied. I invite, invoke, focus, concentrate, manifest and sustain the Opalescent Transformation Flame.

The Ngram chart for "lightworker" (blue line) and "Lightworker" (red line) for the period 1950–2008shows a major rise in frequency of occurrence between 1996 and 1998, followed by a substantial drop-off the next year:

But it would be inaccurate to say that the enthusiasm for the term had effectively expired by the turn of the millennium. One measure of its persistence is the number of titles that continue to invoke the term in just the past ten years. Here is a partial list of such titles, drawn from Google Books search results: Lisa Gutowski, Beyond Techniques: The 2012 Shift: Evolving From Lightworker to Light (2008); Michael Feeley & Sarah Feeley, Walk Into the Light: The Journey of a Lightworker Duo (2009); Tina Erwin, The Lightworker's Guide to Healing Grief (2009); Zsa Zsa Tudos, I Eat That I Am: Energy Intake of a Lightworker: A Revolutionary Approach to Eating and Cooking in Seven Steps (2010); Nancy Griffin, Are You a Lightworker, Eagle, Chosen One, Child of Light, Alien Soul? (2011); Sahvanna Arienta, Lightworker: Understand Your Sacred Role as Healer, Guide, and Being of Light (2012); Wendy Stokes, The Lightworkers' Circle Guide: A Workbook for Spiritul Groups (2012); Sahvanna Arienta, The Lightworker's Source: An Enlightening Guide to Awaken the Power Within (2013); Diana Kushenbach, Messages from the Enochian Tablets: A Lightworker’s Guide to Energetic Clearing (2013); Jack Moore, Stepping Into the Light: The Journey to Being a Lightworker (2014); Michael Golzmane, Grounded in the Light: The Lightworker's Guide to Achieving Balance and Integration on the Path of Ascension (2014); Jan Carslake, A Lightworker's Guide to Fourth Dimensional Chakras (2014); Napoleon Hill, The Lightworker (2016); Tim Drown, The Lightworker: Awakening (2016); and Sahvanna Arienta, Lightworker Relationships: Creating Lasting and Healthy Bonds As an Empath (2016).

That doesn't look to me like the late-stage evanescence of a forsaken term of esoteric art. To the contrary, it looks like the output of a growth industry. That being the case, it is difficult to understand why an existing entry for lightworker would have vanished. All we can say from the evidence here is that authors are continuing to churn out books about lightworkers, and meanwhile Wikipedia has elected to stop acknowledging their existence.

A recent coinage that appear to refer to a worker characterised by more social and ecological commitments:

Lightworker:

• (New Age beliefs) A person driven and motivated to do work which makes the world a better place, improves people's lives, and/or elevates people to a higher level of consciousness.

Usages:

*2002: Joshua David Stone and Gloria Excelsias, The Universal Laws of God, p340

• A Twilight Master is a Lightworker that is working for both the light and the dark side of life.

2003: Carolyn Porter, The Realness of a Woman: A Journey For Seeking, Remembering & Being Who You Are, p274

• I am a lightworker who chose to come here and shine my light throughout the world.

2007: Christopher Penczak, Ascension Magick: Ritual, Myth and Healing for the New Aeon, p501

• 
  One of the key focuses of ascension lore is on "the light". People on the ascension path talk all about the light. A self-chosen label for many is the term lightworker.

(Retrieved from Wiktionary)

A lightworker, is a spiritual person who believes that they're incarnated on Earth in human form for the specific purpose written in their soul's divine blueprint. This purpose is to raise the vibration of the planet (see: The Law of Vibration) and spread light-based energies to the earthly dimensional plane (see: Dimensions, Universal Tree of Life; also Sefirot and 10 Dimensions of Reality in Kaballah). Lightworkers basically believe that they are here to share and spread the light that is currently in existence. ^source

Enlightenment is the common, shared goal of Lightworkers and Masters. When a person has a higher understanding of spiritual concepts, they are generally referred to as enlightened. However, in truth, being enlightened means holding a certain amount of Light. - gaia.com

Lightworkers are not associated with any specific religion, or earthly organisation. It's a different perception of reality (belief system), similar to Kaballah (an ancient spiritual wisdom) which explain that the universe is made of different dimensions of reality (see: string theory).

In other words, "light work", means light doing (spreading the light). So by doing "light work", they help humanity to ascend (also known as spiritual awakening) to higher vibrational planes of existence (similar as Jesus did or other ascended masters).

Lightworker term could be new, however ancient spiritual texts such as Bible is using "light" in many verses. For example, about having light within ("your whole body also is full of light" - Luke 11:34-35; "you are the light of the world" - (Matthew 5:14), so it's a similar concept (about spreading the light), given the right interpretation. Basically, lightworkers believe that they're made of light (a manifestation pattern of electromagnetic energy, an intelligent energy), as everything else in the universe (see: holographic universe theory, consciousness as a state of matter).

It's worth to note, that there is also a similar term: a starseed.

The differences between these two types of individuals has to do with the soul's origin, their core objective, and the foundations of their expertise.

Both are on the planet to uplift the energies of light.

Source: "Lightworker" vs. "Starseed"

Read more: What is lightworker?

Lightworkers are those who volunteered, before birth, to help the planet and its population heal from the effects of fear. Each lightworker is here for a sacred purpose. Very often, however, life on earth with its material focus creates a form of amnesia in lightworkers. They then forget their divine and perfect identities, and also their abilities to miraculously help the earth and all living creatures. When lightworkers forget their true identity and purpose, they feel lost and afraid.