I have the same issue: all the mirror repositories give a 500 error, thus their settings panel is unavailable; can't delete repos, can't delete the account.
Yeah, I have a mirror that responds 500 also.
Three weeks ago I've sent an email to the NotAbug's Administrator
( https://notabug.org/about#whoweare )
Requesting my account deletion, with links to these bug reports:
#225 (2 months old)
He hasn't replied, yet.
I'm starting to think that nobody is actually checking these bug reports.
Bugreports are being checked but due to real life things time has been very limited. Please bear with us this will all get sorted.