Your authenticator code will be on whatever device you added it to whether it be a cell phone or the computer you're using. If it's on a cellphone I know Android has an app called Authenticator that looks like a metallic G. When you click on it there should be something that says Jagex gives a 6 digit code and has whatever name you provided at the time you set up authenticator.
If you don't have access to the device you set it up on then you'll need to request authenticator to be disabled in the account section of the website and they'll send out an email to your registered email address you'll need to click on to disable authenticator.
When the day becomes the night and the sky becomes the sea, when the clock strikes heavy and there’s no time for tea; and in our darkest hour, before my final rhyme, she will come back home to Wonderland and turn back the hands of time.