At this time, no. You could edit a user file and write something else inside the file, which would invalidate their password and prevent that exact name being used again; but the forum places no limit on how many accounts any one person could have, so it wouldn't prevent a user from posting in any way. A temporary IP ban would be the only real option and for now that has to be managed manually using your server's logs and controls.

Adding banning would add a lot of complexity and for the most part would be very ineffective (due to the anonymous nature of the forum), if I do implement it in the future, it would go hand in hand with a lot of other control features.