Today Facebook finally unwrapped the Facebook Home for Android phones mystery. It's quite interesting and potentially Facebook won't even need its own device. Check it out.
If any file can not be deleted, then you can use the program LockHunter, which removes the active connections of other applications to that file, which allow you to change or delete file.
Remember the legendary Predator movie with Arnold Schwarzenegger? Those Predator aliens had this thermal view feature so they could their prey even in complete darkness, let's Photoshop it.
Cool thing about Google Drive is you can access all your documents from anywhere and you can actually upload a Microsoft PowerPoint presentation which automatically turns into Google Drive Slide.