Account Owners are in charge of setting up the account and the billing. There can only be one Account Owner per community. To transfer the account ownership to another manager, only the existing Account Owner can make that change.
To transfer the account ownership follow the steps below:
In the top right click the Community Menu icon, then choose Community Settings.
Select the System Roles section, find the manager’s name or email address on the list, click the Role dropdown, and select Account Owner.