This guide should help you with Banning and Unbanning players from your Terraria server. If you're worried about your server being griefed you might want to put a password on your server.

Ban a Player

1. Log into your Command Center.
2. Click on console tab and in the console type in ban playername.

The player must be online in order for the ban to work. If you try to ban the player when they're not online the command will not complete.

Unban a Player

1. Log into your Command Center.
2. Click on the Files tab and locate the file banlist.txt.
3. Click on it to edit and remove the name and IP of the player.
4. Once saved restart your server and the player should be able to rejoin.