I accidentally set a frozen player as the clan owner

The name of my clan is Golurk Mania and I set Mysterious Garden as the owner

Well then thats your mistake and nothing can be done to rectify it unless that person gets unfrozen and when he gets online you can ask him but its completely upto him to decide whether he wants to give you the ownership of the clan back or not , it asks you for a confirmation while setting someone as a owner of a clan so its your fault.