Delete this account
I was successfully mobbed out by User:Metalhead64. As you're also deleting user accounts completely when they don't pass registration (as I noticed when my first attempt to register failed as metalhead declined it without giving any reason, my user account was just gone afterwards and I could register again using the same user name), please do so for this account. I already kicked myself out of the translator group. Thanks and have fun, at least all of you who don't translate to German.
I'm afraid, in any MediaWiki sites, delete an account is not (at least, at this moment) be possible, see discussion in phab:T34815.
Maybe, we should rename you as User:Vanished~something?
As can be seen here, my account was rejected and created afterwards (meaning it was completely deleted when it was rejected at first). I knew that MediaWiki doesn't allow this, but the fact that my account was deleted resulted in my impression that deletion is indeed possible (and as it seems it really is, but from your answer I take that this is not when the account was accepted once. Closing this issue is correct then, just leave it as it is.
Before taking drastic decisions, you should try to involve other translators in the discussion to see if you can find a solution. Please bring the matter up at portal talk:de focusing on how to improve translations rather than on people.
I tried to make constructive edits and got a message that I should stick to the rules of this wiki. It was not explained what exactly I did do wrong and my request to do so was ignored, but my edits were reverted. When making a new discussion at User_talk:metalhead64 I just got the answer "I don't like when new users mess around." (in German, last sentence of link and no constructive critics. I'll take this sentence of a 'crat and sysop on this wiki seriously. Nobody was interested in helping me to make my contributions better but I was subtly told to piss of. Thanks, I'll do so. Goodbye.
To say no more, other discussions on the talk page of this user also don't seem to be anyhow constructive. Answering questions like "How do you know what good translations are" with "The translation must satisfy me." isn't very helpful at all. I would have liked to help here, but I accept that translatewiki can not do without metalhead, as he is the one making most of the german translations and therefore take my right to go.