User roles determine the access level or permissions of your teammates. Forest Admin allows you to set up three different roles :
Admin - can access project settings (manage teams, user roles, and environments), customize the admin UI (activate layout editor) and manage data.
Editor - can customize the admin UI (activate layout editor) and manage data.
User - can only manage data.
You can change a user's role from their details page:
Go to the Users tab of your Project settings
Click on a user in the list
Change the role assigned to that user
Don't forget to save