How to prevent Photoshop CS6 from reopening old files
You just need to delete the temporary saved files from the Photoshop's cache.
I don't know how this began, but I think it was because of a lot of crashes in my OS X Mavericks installation and incompatible version of some apps. The Photoshop went crazy and still opens old files even if I delete them from their original folders.
The solution? Remove these files from Photoshop's AutoRecover folder.
1. After the Photoshop start right click the file tab and select Reveal in Finder function
2. The AutoRecover folder will appear. Delete the files in it
3. That's all.