That's strange... I'm currently not near my gaming pc, but what You try is navigating to your Documents folder and open the My Games folder. There should be a Final Fantasy XIV A Realm Reborn Folder there. Look for a patch folder and clear it's contents.

Be sure to make a backup of the Final Fantasy XIV folder before you do!

If you play on a PS3, you might need to remove Final Fantasy XIV installed Game Data, but since I do not own the PS3 version i'm not sure if that's correct.

Can anyone who owns the PS3 version verify if what I said is in fact correct? Thanks.