Joseph Reagle
the resource is intentionally unavailable
the server owner desires that remote links to that resource be removed. (Fielding et al. 1999)
Cyberlanguage
Disengaging from the Internet via the deletion of all your publicly available information. (quadhome 2011)
proclaim[ing] that they are leaving a community forever… leav[ing] a long ass, boring, nonsensical post explaining why they are so much more highly evolved than anyone else in the community. (Dramatica 2011)
“It’s time for me to find a new hobby. Preferably one that doesn’t involve angle brackets. Or computers. Or electricity.” (Pilgrim 2004 qtd in rileyw 2011)
I recently returned to photography after a long absence…. If you’ve written to me in the past few years and I haven’t responded, I apologize; and if you’ve known me that long, you probably already know why.

I have lost all my belief in the wikimedia projects. On some projects I still have moderating bits, I hereby ask the stewards to take these bits away as I do not wish to spend too much time anymore on the projects, I might shout a bit from the sideline. (Kalken 2006)
Bye bye. Don’t let the door hit you on the way out, you whining prima donna (Anonymous 2010).
If anyone is in direct contact with Mark, please let me know that he’s okay …, even if his internet presence has been erased. As much as I hate for the world to lose all of the incredible information he’s created and shared, that would be as nothing compared to losing the man himself (Meyer 2011)
Mark Pilgrim is alive/annoyed we called the police. Please stand down and give the man privacy and space, and thanks everyone for caring. (Scott 2011)

… can be an antecedent to suicide
It can also be graduated.