The easiest way to hide a team from the front end of the event is to delete the team.

If the team is not deleted from the event, it is difficult to minimize their appearance on the front end.

Alternative solutions to not deleting the team:
  1. Prevent future participants from joining the teams by disabling the option to join a team. This is a global event change and will be applied to all events. It can not be specified by team.
  2. Disable future donations made to teams. This is a global event change and will be applied to all events. It can not be specified by team.
  3. Make team donations hidden or undisclosed. This is possible through a participant's HQ.