Make sure you\'re spelling the name correctly, both when you try to delete and when you\'re trying to log in the game.
Asides from that, I have no idea why it would say your account is valid. You could always just create a new one.

To my knowledge, accounts are only corrupt if you linkdead while uploading a new char. However, if your account has been working for a while and then you received a database error, you might want to speak to the devs directly to retrieve your items/crystals.
IRC Public Development Channel
server: irc.freenode.net
channel: #planeshift