Yes, please. Certainly not a "need to have" but useful from a user perspective.

There was an extension, CloseMyAccount was its name IIRC that could very
well be used to do this; but it is hosted on Wikia, etc.

T166858: Deploy "CloseMyAccount" extension to allow disabling/closing your own user account

Suggestion from someone else to add a confirm option, so no one would accidentally click on the vanish button.

Thanks @Trijnstel for adding my comment from the list. Yes. I think requiring two clicks to confirm they actually want to vanish is important. Even if only an edge case, we would get people who claimed to misclick and submit. This would eliminate that problem.

In T195888#4242485, @TonyBallioni wrote:

Thanks @Trijnstel for adding my comment from the list. Yes. I think requiring two clicks to confirm they actually want to vanish is important. Even if only an edge case, we would get people who claimed to misclick and submit. This would eliminate that problem.

Or have a [[Special:GlobalRenameRequest/vanish]] and another mandatory "CONFIRM" button before they can submit?

Actually, I think this would be better since by separating the main rename request and vanish request (with mandatory confirmation), nobody would click "vanish" by mistake.

What about "just" adding a checkbox on the existing [[Special:GlobalRenameRequest]] page, that disable the new username textbox and fill it with random and untaken username ? Creating a new dedicated subpage looks not necessary to me.

@Framawiki: @revi was responding to my comment above about making sure there was confirmation for the intent to vanish using this method. I think a dedicated page or some sort of confirmation to the decision to vanish would be important, otherwise I'm pretty sure we will be getting emails/talk page posts about accidental vanishings.

Change 528205 had a related patch set uploaded (by Urbanecm; owner: Urbanecm):
[mediawiki/extensions/CentralAuth@master] [wip] Create "vanish" option in Special:GlobalRenameRequest

https://gerrit.wikimedia.org/r/528205

In T195888#5393771, @gerritbot wrote:

Change 528205 had a related patch set uploaded (by Urbanecm; owner: Urbanecm):
[mediawiki/extensions/CentralAuth@master] [wip] Create "vanish" option in Special:GlobalRenameRequest

https://gerrit.wikimedia.org/r/528205

This adds a checkbox "Request courtesy vanishing", which a) hides "Requested username" field b) generates a random username "Renamed user xxxxx", which is then used for the request.

Two potential issues with the patch:

• I didn't find a way how to mark a field as "not required" from JavaScript. I can do $('#mw-renamerequest-newname > input').prop('required', false);, but that would make MediaWiki backend yell with "This value is required.".
• I didn't find a way how to hide a field, without adding a CSS class to cssclass attribute in getFormFields(). Hence, I added mw-globalrenamerequest-newname and hope someone will guide me.

Also needed....

• Check if the requesting user is blocked (esp. hardblocked) on any WMF project & pre-populate a decline message if so.
• Default tick the suppress redirects checkbox
• Delete all their userspace pages except their top level user talk page, on all WMF projects (this is currently beyond the privilege set of stewards & renamers, it ought to be built in to the renaming tool)

Then RTV requests can be done consistently and to the full extent that users want.

An unvanishing tool to revert all the vanishing of users who continue to use their account wouldn't go amiss.

In T195888#7518352, @Cabayi wrote:

Also needed....

• Delete all their userspace pages except their top level user talk page, on all WMF projects (this is currently beyond the privilege set of stewards & renamers, it ought to be built in to the renaming tool)

Simply having a page such as "User:Username/SomePage" exist doesn't confer any special global privileges to have the page deleted on every project - especially if it has derivative versions authored by other editors. The same may also apply to pages such as "User talk:Username/Archive1", where the archives have been produced by moving revisions from "User talk:Username" rather than just copying and pasting.

In T195888#7518376, @Xaosflux wrote:

In T195888#7518352, @Cabayi wrote:

Also needed....

• Delete all their userspace pages except their top level user talk page, on all WMF projects (this is currently beyond the privilege set of stewards & renamers, it ought to be built in to the renaming tool)

Simply having a page such as "User:Username/SomePage" exist doesn't confer any special global privileges to have the page deleted on every project - especially if it has derivative versions authored by other editors. The same may also apply to pages such as "User talk:Username/Archive1", where the archives have been produced by moving revisions from "User talk:Username" rather than just copying and pasting.

I second @Xaosflux's concerns here. Local communities need to have autonomy over deletion decisions. There are currently unblocked users (with a block history) where deleting those pages could very easily lead to a controversy. Only locals can spot those cases, and deletion decisions should be left to them where possible.

Let me also link https://en.wikipedia.org/wiki/Wikipedia:User_pages#Ownership_and_editing_of_user_pages -- while it's strictly speaking an enwiki-only policy, same principle is adopted by several other projects. It says "Traditionally, Wikipedia offers wide latitude to users to manage their user space as they see fit. However, pages in user space belong to the wider community. They [...] do not belong to the user." (emphasis mine). In another words, the community (at least at enwiki) is fully authorized to decide to not allow a removal of a page, if it thinks that's an appropriate action.

See the iOS app for some UI inspiration.