Through Contact Bulk Data Management, you can remove or add users to specific groups.
1. In Report Type set Groups
2. Set Contact Type (i.e. Boarder)
3. Select Load Data
When the list generates you will see a Groups filter appear above the load data button together with the editing options.
1. Select the Group(s) that you want to alter
2. Select the READ ONLY MODE button. This will change the state of the screen to give it editing ability
3. Make your changes and be sure to SAVE your changes