Q: my icloud is connected to non existing unrecoverable gmail address

hi.
my icloud is connected to an email that is no longer exist. and google says it is unrecoverable.

moreover, when i want to restore the password, it says, that apple id doesnt exist

at the same time i have and use another apple id on my phone without any problem.

the only thing i want is to unbind my phone from a nonexisting icloud account