help getting rid of old password on my iPhone and getting my computer account to match my phone as it has a different account.

I can't log into my apps on my phone because my phone has an old email address and I have no idea what the password is. I want to upgrade my iCloud but when I try to open my apps, it brings up the old email address and wants me to put in a password. I have tried everything I could think of, so I requested to get my password reset but it never was reset. I have gone to settings but my phone is an older model so I can't find a way to update my email on my phone or how to delete it. I do have an account on my computer with a different email that I set up a while back but I don't know who originally set the old one up. Could have been my daughter or a foster child I had.