1. Turn off your Android device.
2. Press and hold the "power", "volume down", and "camera" buttons simultaneously. ...
3. Release the buttons once your Android device is powered on.
4. Scroll using your "Volume up and down" button until you find the "Factory Data Reset" option.
Sign in to Android Device Manager with your Google account on a PC/Mac and change the password. If that doesn't work, then you might need to factory reset. However, be aware that all your data will be deleted from the phone.
Welcome to Android Central! An additional word of advice for the future--if you're prone to forgetting passwords, write them down on a piece of paper and keep them secure at home, like in a safe. The backup password is there exactly for this reason--fingerprint sensors can fail.