Clear a temporary code by first entering your main entry code on the keypad. You will need to press a combination of keys particular to your model of opener, followed by the temporary code you want to clear. In some cases, the door opener will beep or flash lights to indicate progress. Check your instruction manual for exact instructions.
Enter your garage via another entrance to access the mechanism. Clear your master code by pressing the appropriate button on the motor and then entering an alternative code on the keypad. Once you enter the code, you will need to press and hold the "OK" or "Enter" button until the garage light blinks or indicates a successful code reset. You may need assistance to complete this task if your keypad is a significant distance from your garage door since some models of garage door opener impose a time limit for you to finish. Check your manual for exact details.
Enter a new code into the keypad and then press and hold the "OK" or "Enter" button. Press a combination of buttons inside the garage on the motor or the control panel by the exit door. The exact buttons you press will vary depending on your model of garage door opener.