CB Privacy can hide them using the Profile Privacy field. If set to Private for example they won't show up.
The best way however for permanently removing specific users is either usergroups or Filters on your userlist. Example as follows would exclude specific user ids.
Filters
Advanced:
Code:
ue.`id` NOT IN ( 42, 39, 12 )
You'd basically just have a comma list of user ids. In this example users with an id of 42, 39, and 12 will never appear in the userlist. Advanced filters let you directly add to the WHERE statement of the userlist query so you've quite a bit of control over who is shown.