If you're a team manager and you want to completely remove a team, follow the instructions below.
You must be the team manager who created the team.
How to Remove a Team Forever
Go to the Team settings
Scroll to the "Danger Zone" at the bottom of the page
Type in "DELETE" in all capital letters
Select "Delete Team Forever
That's it! The team will be removed from the system and all players connected to this team will no longer be able to access it, including past seasons.