I set a password on my phone yesterday and now i

Then you have to contact your nearest Apple store or Apple service center.

Well if you don't want to go to a Apple store nearby . You can also restore your Iphone with iTune to the nearest date. Plug in your IPhone with iTune click on Restore and choose Restore from a back up. If the password still appear after the restore completely restore to factory setting will surely delete all the password you have :) . Good luck and keep me updated.