You can't, if you don't want to use them anymore just never log in on them again :)

lol

what do mean...delete nicks....LOL

Yea, be super super 

bad

 and get in trouble.....Then they 

ban ya

 hopefully permanently. Ha ha Fod Im just joking.  But its a thought.

actually if would be a good idea to delete nicks which haven't been used, for example, for 2 years,so people don't have to make nicks like AAAAA7237632,cus all others are already taken