Deactivate returned device in Apple ID

[Anth9]

I have swapped a iPhone 15 for 16 pro and sent back . I have been asked by sky to deactivate find my phone to be reused, issue I have is I have no recollection of my old number and sents any activation numbers to that number I don't have and can't deactivate this , can you help.

[twilight+princess]

Did you sign in to your Apple account & turn off find my phone & remove the phone from your account in order to remove activation lock? If not then you should be able to still do this. If 2fa is enabled then you'll need to use one of the recovery codes created when you set up 2fa.

[Anth9]

Wong let me sign in as asks for phone number I can't remember 

[twilight+princess]

https://support.apple.com/en-us/108934
Just tried the instructions no code was asked for.