If the team no longer exists or team members have moved on, the Admin is able to delete an entire team. Here's how:
First, the Admin should start in the 🏡 Team/Home tab
Then, select the ⚙️Settings
Scroll to the bottom of this page and Delete Team
Note: once you delete a team, this action cannot be undone. Everyone who is part of this team will no longer be able to access this team.