Proper way to reset an iPhone if you've forgotten iCloud Password

Hi,

I have an iPhone 6 that I'd like to reset. However, there is an "unverified" iCloud linked to the iPhone preventing me from resetting it traditionally. This was an old phone that I've recently pulled back out; however there's an old "unverified" iCloud account that I can't remember the password for (don't have access to the email to reset the password either). When I try to sign out, it asks for the password to turn off Find my iPhone.

I can use the phone completely fine right now, but I just want to reset so I can link it to my current Apple ID. If I'm not mistaken, if I reset it through iTunes or through the Settings, the next time I turn on the phone, it would require me to enter the previous iCloud password registered on the phone or it'll block me from using the phone completely. Is there a proper way to reset it and remove that iCloud account without locking me from my own phone??

Thanks,

J