what is procedure for restoring password on an 11 phone when you only have access to an HP computer

You mean recovering the passcode to unlock the phone? If so, it doesn’t matter if you have a Mac or a PC as long as you have the latest version of iTunes installed you can restore the device by erasing it in iTunes.

If you forgot the passcode for your iPhone, iPad, or iPod touch, or your device is disabled - Apple Support

After you erase the phone to unlock it, you can restore a backup if you have one and then set a new passcode.

Do this: https://support.apple.com/en-us/HT204306