there is both a ‘ban’ and a ‘warnings and suspensions’ plugin available on our plugins download page…

if you unsure about using SP plugins this guide should help:

http://codex.simple-press.com/codex/plugins/plugin-basics/using-plugins/

think Andy misunderstood the question…

with the Ban plugin, if users have the SP Manage Users capability, they can use ban users…

with the Warnings and Suspension plugin, users with the SP Manage Warnings capability will be able to warn, suspend and ban users…

permissions are for the front end…  capabilities are used in the admin… by default moderators have access to the admin so they just need the capability… you can give it to them on forum – admins – manage admins…