How to turn off Face ID (with reference to Use Face ID on your iPhone or iPad Pro - Apple Support ):
Go to Settings, then tap Face ID & Passcode.
If asked, enter your passcode.
Turn off the toggle for iPhone Unlock through Face ID.
If you still have questions or problems:
Refer to this document for ways to contact Apple --> Choose your country or region - Official Apple Support
Select your country (also look for "other" regions), then a product. If you don't see one that handles your issue then keep experimenting with selections until you reach one that gets you a chat session or a telephone call and get the representative to redirect you.
or:
Contact Apple for support and service by telephone --> Contact Apple for support and service - Apple Support