Change Phone number. Already registered

Hi there. I have installed revolut in my new mobile. I am using a new phone number and I didn’t realise I had to change it first on the old mobile. I started set up on new mobile providing new phone number. When I realised I should change phone nu ber on old mobile first it was too late. Old mobile revolut says: phone number has already bbeen registered.
How can I unregister the new number? Can tech support help?
I have tried via chat but there is 6 hours waiting time.

unfortunately not much you can do except wait for support.

I have the same issue.

How can I unregister a phone number so that I can change again?