Open the Settings app
Tap Face ID & Passcode or Touch ID & Passcode
Enter your passcode
Turn off Face ID or Touch ID for the features you want
To disable Face ID or Touch ID completely, reset Face ID or remove all enrolled fingerprints
To stop biometric use for Apple Pay, turn off Face ID or Touch ID for Apple Pay
To stop biometric use for app and password autofill, turn off Face ID or Touch ID for those options
To require passcode only, keep biometric options disabled and use your passcode instead