How to unlink one of my apple accounts to my phone??

I have two different accounts and I only use the one. I’m signed into it but I went to update my apps it’s using information for the other (old) account (that I don’t even remember the password too) and not even giving me the option of switching to another account. So then I’m not able to update....It’s just automatically assuming it’s that account I don’t even use anymore. Which doesn’t make sense to me considering I don’t even use the old one anymore and I stay signed in my new one.

my apps are not working cause they need updated and I have no idea what to do.

I can’t remember the password to the old account but I’m trying to change the password thinking maybe I can do something once logged in to the old.

my question is do I need to try to get into the old account and delete it and then maybe it won’t be linked with my phone or is there some other way to unlink it??????