You can transfer members from one team to another within your account by first adding them to the new team and then deactivating them from the old one.

Go to the Teams & People page and select "Edit members" from the menu of the team that you want the person to be transferred to.

Then click the “Add team members" button, and then "Add existing team members." Select the person you want to move from the list.

Then, go back to Teams & People, select "Edit members" for the old team, and deactivate them from the team.