Use a PUT request to /v1/teams/:id to change a team. You can change the team name, make one or more users leaders of the team, or and/remove members from the team.
You should always send the complete list of User IDs in the userIds and leaderIds fields if the field is present in your request. To remove a user from the team, first make a GET request to /teams/:id to get the current list of users, remove the ID you wish to remove from the team, and then send the now changed full list of user IDs back with a PUT request to /teams/:id.
Similarly, to make someone a leader of the team, or demote someone to a regular member of the team, first make a GET request to /teams/:id to get the current list of leaders, make your changes, and send back the changed list with a PUT request to /teams/:id.