Teams are defined and provisioned with Owner, Assignee, Approver, and Viewer roles. Then, rather than assigning users on a task, the task is assigned to the Team. Administrators and Power Users can add, edit and delete teams.
To create and manage teams,from homepage goto Tools > Access Control> Team> New.
You can assign backups for the Assignee and Approver roles only when the primary user is a named user, not a team or group.
See below video for demo on create and manage team.
To delete a team,from homepage goto Tools > Access Control> select Team> Delete. If a team has been assigned to a task in a template, then it cannot be deleted. To delete the team, first remove it from all tasks to which it is assigned.