Become team admin

An ex-employee previously created a team for our company but we never actually ended up using Miro.  We are now being brought into an engagement through an external agency that requires us to all login and create Miro accounts.  Through the very nature of this engagement, all of us from Brace are being asked to join this pre-existing team this ex-employee had set up under the Free plan.  I need to become the admin of the team to remove this ex-employee and manage the account, please?  Anyone know how I can do this in the free plan or if there is something else I should do?  Let me know!