Apple system charing problems

i use apple to charge my gpt pro ,however , when i wanna change my subcription to another account , my pro still on my first account ,not my second account . i did cancel the first account’s pro subcription ,and until its ending , i make the subcription on my second account. when this time ,my phone told me that my apple account was connected to my first gpt account ,and cannot change to subcribe the second account .so can u provide any help?

so how can i cancel the connection between my apple account and my first gpt account.