Team leaders (and agents with the appropriate access rights) can delete team squads by going to: Your Team > Manage > Squads. Click on the squad you want to delete (as if you're going to edit it), then look for the red Delete Squad link at the bottom right of the page.

Note: Deleting a squad will unassign all team members associated with it. Any batch stats that were previously linked to this squad will also be disassociated.