Teams are administered within Home -> Settings -> Teams. Within this interface you can add, edit, or remove a team. You can also add or remove users from a team.
You can create a new team with the New Team button at the top of the team list.
Or you can click on a team name to update or remove that team.
You can also, within the edit screen for the team, add users by clicking the plus at the top of the members section.
You can also remove members with the red X on each member line.