Browsing around imgur, I can't find a way to get rid of my account.
The Terms of Service say, "Don't upload copyrighted material, harassment, spam, gore, pornography, or especially child pornography. If you do, we will ban you, delete all your images, report you to the authorities if necessary, and prevent you from viewing any images hosted on Imgur.com."
So, I suppose you could try uploading some gore?
SERIOUSLY, though, just use the contact form and request deletion. I'm sure they get them all the time.