if his name is ssjgoku1312
type in your console
kick "ssjgoku1312"
easy as pie <3
if there name has a ~ in it, then open the console and type status
you'll see a list of players and their nubers
let's say superduperman is player #3
kick #3 I think..don't remember, haven't hosted in about 2 years since beta 1.0..