This error occurs when the existing admin user email is updated with an email address that is already associated with another account.
Please search for the Admin user if it already exists. If not then that email address must be associated with Major Admin.
IIn this case you need to contact CSM or raise a request on Support@punchh.com.
If further assistance is required, submit a ticket to Punchh Support. (For help submitting a ticket, click here)