I want to transfer the wall ownership
Go to https://walls.io/me and enter the email address of the new wall owner. After you are done setting up the wall for the next person, log out.
The new admin then should go to the login window and after entering his email address, should click on "I forgot my password" to receive an email to set up a new password.
Please be aware that changing the account owner does not change the person who pays!
I want to change the person who pays
Go to https://walls.io/me and click on "edit my address/add VAT ID".
In the new window click on "edit subscription".