To transfer ownership of a Stripe account to someone who is not already a team member or user on the account, they must first be invited to be a user on the account and accept the invite.
Log in as the current owner, and go to the Team settings under Business Settings.
Click New User.
Add their email address, set their role to “Administrator,” and save to send them an invitation to join the account.
Once they have accepted the invite, go back to the Team settings.
Click the Edit button next to their name.
From the popup, select the option to Transfer ownership to this user and save.