You can transfer your application by following the steps below:
1 - Log in to your account;
2 - Click at "Server Settings" button;
3 - At "Core Settings", click on "Settings";
4 - Scroll down and click on "Transfer App" button;
5 - Provide the email of the new app owner;
NOTE: The new owner needs to be registered on Back4app first.
6 - Click on Save button.