how do i change apple id

See the following instructions from Apple for information on changing your Apple ID to a new email address: Change your Apple ID - Apple Support

Are you looking to add or remove payment info, or change an email address, add a recovery contact or enable two-factor authentication, or is this possibly related to Activation Lock?

If this is Activation Lock, that’s intended as a theft deterrent, and deliberately not easy to bypass. Only the person holding the Apple ID and password can clear Activation Lock, or somebody with the original purchase receipts showing serial number or such, or other legal paperwork sufficient to convince Apple. If Activation Lock is set on an iPhone or iPad you have acquired, contact the person that sold it to you. Otherwise, the iPhone or iPad will be useless to you, and probably best recycled. Apple won’t unlock it, and we cannot.