Using the User Properties Dialog to Manage Which Groups and User Lists an Individual User is a Member or Owner of

Select the Users node.
Right-click a user and select Properties.
The User Properties dialog opens.
To manage the groups and user lists the user is a member of, select the Member Of tab.

To add this user to a group or user list, click Add, then select one or more groups and/or user lists in the Select Groups and User Lists dialog and click OK. These items are added to the Member Of tab.

or
To remove this user from a group or user list, select one or more groups and/or user lists in the Member Of tab and click Remove.
To manage the groups and user lists the user is an owner of, select the Owner Of tab.

To make this user an owner of a group or user list, click Add, then select one or more groups and/or user lists in the Select Groups and User Lists dialog and click OK. These items are added to the Owner Of tab.

or
To remove this user's ownership of a group or user list, select one or more groups and/or user lists in the Owner Of tab and click Remove.
When finished making changes, click OK in the User Properties dialog.