You can view all the members in your group by clicking on the View Members hyperlink on the Group Administration page.
From this screen, you can deactivate the user (this is the same as denying them membership to you group) by clicking the “Deactivate” link. The second option will be either “Review Requests” or “Allow to Post” depending on the current setting for the member. If you click on “Review Requests”, it means that any requests submitted by this user will need to be reviewed before others can view it. If you click “Allow to Post”, it means that the user will not require approval when posting requests. You can also make a member a group administrator from this screen or remove the ability to administer the group. You can have as many administrators as you want.