When you are 100% sure that you want to delete the team or multiple teams, then complete the following.
On the stack or block, select the team(s). From the stack, select a team or multiple teams. Hold the Ctrl key + click the different teams to select multiple teams. You can also, hold the Shift key and click the first team and then click the last team which will select all teams between those two points.
From the Information Panel, click the Teams tab.
Click the Delete button. The warning message displays Are you sure you want to delete the selected team? This includes blocking, clearing people from the team, and removing the team from any associated scenario plans.