How do I change my password or find it

You cannot combine accounts. They are forever separate and independent

You will need the passcode for it, if you want to remove it from a device.

If you no longer have a device signed into the account, then you will have to try to reset the passcode through the iForgot website as explained the link I posted above: If you forgot your Apple ID password - Apple Support

Reset your Apple ID password on the web

If you don't have a trusted device, you can reset your password on the web—but the process might take a little longer.

When possible, the web process redirects you to a trusted device. If you'll have access to one of your trusted devices soon, it might be faster and easier to reset your password then.

Reset your password at iforgot.apple.com

Follow the steps here: link-> If you forgot your Apple ID password - Apple Support

It’s normal because I had to generate a new account for my Apple ID and iCloud. Trying to retrieve now would be the Apple ID before I generated my new account. Just want to combine them both.

I’m not signed in with that account and don’t have that phone number anymore either.