You have a couple of possibilities to react to this.
For example you can simply delete unwanted comments or guestbook entries.
You can also switch comments or guestbook entries off or use the option to
hide them before you approved and activated them. So, you can avoid future
unwanted comments. These options can be changed in the preferences of your
weblog.
If you experience major difficulties with another user or if someone writes criminal
things, you can use the "Complaints" link at the bottom of the blogigo website,
to complain about the user.