Edit team members names
I would prefer to edit the display names of my team members in MS Teams (free). At this point I am not able to do this.
Remi Lepage commented
You can have access through this account: admin@NameOfYourOrganization.onmicrosoft.com
You will need to "reset/create" a password sending a PIN to your personal email. Then you will be able to login and have access to the Admin center.
From the Admin Center, Users, you will have access to change the Display name of every users.