Handle users.

Is there a way to block a particular user from posting?
If not, is there a way to prevent a particular user from logging in, without banning them?
Thanks.

Make a hidden group & disallow its permissions to post for that forum.
Add the user to that group, it should do as you like then.

Thanks.  Can you tell me the exact way to do that?
I see how to give permissions to a regular user but not how to take permissions away.

Hello,

Go to the forums' permissions  
Admin panel > general > Categories and forums > Permissions:
Uncheck the box for that created group
> Save

Do this to all forums

Okay,thanks!