My forum got spammed. How do I delete those posts and block this person from doing this again?
IP Banning is the solutation of blocking people, But rember they can always register with a proxy so make sure you install anti proxy mods to prevent them from re accessing your site.
There are many anti spam Plugins, install reCaptcha on registration.
You can delete all post my particular member.
Honestly, you don't really even need recaptcha if you give RegSecurityQs good, hard questions. I haven't had a spambot get through since doing that, having SFS, and Register Time on.
I do keep a list of common spam IPs and block them, however.