You may want to use bans and unbans on your server to punish any players that break your server's rules. You can do this in a few different ways, check it out.
Use the RCON Console
1. The easiest way to handle bans/unbans is by using the RCON Console. You can find a guide to setting it up here: RCON/Console Article
2. Enter ban <playername> or unban <playername> into the console to perform the action.
1. Enter your Server with an Admin account (don't have one? find out how to create one here)
2. Make yourself admin with /admin
3. Enter /ban <playername> into the console
1. Follow steps 1 & 2 in the section above
2. Enter /unban <playername> into the console