Lost my Sims 3 Supernatural game disc and installed The Sims 3 Dragon Valley

dragon valley is a world (store item )  found in the main menu +new game to start playing in  the world you still play from whatever game you normally play from which in your case is supernatural   you can if you wish uninstall the disk version of supernatural via control panel uninstall the manually search for left over files and registry keys and or if you have ccleaner from piriform run that few time to assist with the left over files and registry keys then log into your origin account if your game was registered and download the digital version of your game to start playing again with your supernatural

http://help.ea.com/en/article/the-sims-3-supernatural-manual-uninstall/

also if you run into a DLC alert while downloading the supernatural ignore it and do this to be able to install the download version without reinstalling despite that message, do not click on the download button in origin click on the “i” (information) button  this will open another window that also has a download button click on that to install