The best method is to use your filters to remove several contacts from groups. 

  1. On the left navigation, click Leads & Contacts > Contacts.
  2. At the top of the screen, click the Filter button.
  3. Under the Included Groups field, input the group you want to remove contacts from. 
  4. Click the X to go back to your contact list view. 
    • Your contacts will dynamically update when changing your filters.
  5. Check the box next to each contact name you want to remove.
  6. At the top of the screen, click Actions > Set Groups.
  7. Toggle the Remove Groups option then choose the group(s).
  8. Click Submit.