I forgot my apple id and how can I reset this device and

You need to log out of the old ID before you can sign in with the new ID. If you reset the phone, you will probably get an Activation Lock.

See if you can recover the ID/password. Use every email address you can think of.

Apple ID - How to find your Apple    An iCloud e-mail address is an Apple ID.

Apple ID - Find              

For the Apple ID password, enter the Apple (iCloud) ID and click Forgot Password. See if you can get an email option if necessary.

Apple ID - Manage            

Apple ID – Forgot Password            

If necessary, if you are the original owner, contact Apple. Apple can remove the Activation Lock if provided the required paperwork. Either take the device, the original purchase receipt with the serial number, and a photo ID to the nearest Apple Store (if it has reopened)

Genius Bar Reservation and Apple Support Options - Apple.    

or contact Apple ID Support. 

 Apple ID - Official Apple Support.    

Contact Apple for help with Apple ID account security - Apple Support.      (Link doesn’t always load)   

Get Support   https://getsupport.apple.com        Work through the screens to get a chat option. 

Apple Support schedule phone call        

https://twitter.com/AppleSupport       People have posted it may take an hour or more to get a response.