I have an old email that no longer using can’t remember password

But when I tried using the first email as an Apple ID it said it’s not an Apple ID I can’t update my phone backup nothing on the cloud how do I get rid of the first email that’s iCloud one other is the store one

No it dont work it keeps asking me for the first email password the one that Apple said ain’t no Apple ID it pretty much controls everything always popping up asking for password after all it controls my iCloud the other the store

I bought it second hand from family it is carrier unlocked that’s why I wanted it I mean I’m still using it I just can’t update or backup and few other things

I bought it second hand from family member it’s a carrier unlocked cell I still use it like always I’m just limited to no updates no backup and a few other things

No they don’t have it no more and don’t remember the password

I also got a iPad 2nd gen A1395 that I bout at a swap meet it has a four digit passcode I don’t know it either how do I get past that