I want it completely removed from the database. Everything.

No trace that "XanthosGambit" was ever an account on e621.

The delete account page outlines what it does, which effectively just anonymizes your account, rather than a full database removal.

If you want more than that, you'll probably have to contact management - though it's unlikely they'll oblige.

It's impossible to completely delete any trace of your presence here, at least not without the cooperation of every single user to ever quote you (or if you can convince management to edit others comments, which is unlikely). Comments that quoted you will always start with "[redacted]* Said:", with a link to your deleted account with the new anonymized name "user 427380".

(*I'll at least edit out reference to your name if you delete your account)

This is a bit like asking Wikipedia to remove your edits. For example, you edited posts. But divorcing your identity from the account is possible.
BTW, you can completely hide all your comments.