After 5 failed unlock attempts, tap Forgot pattern?. Note: The device must have already been associated with a Google account for the 'Forgot Pattern' option to display. If your Google account was not added, you must do an alternate factory reset of the device. Search tutorials for ‘reset’ for Reset Device instructions.
To unlock via backup PIN, enter the PIN, then tap OK.
To unlock with your Google account, enter your username and password, then tap Sign in.
From this screen, the screen lock method can be adjusted.