Removing OSX without deleting media files
If you have a spare USB hard drive (or Dropbox/Google Drive/Box.com/iCloud account big enough to hold all your media), I'd just move your media files to that temporarily.

Boot into OS X Mavericks, open Disk Utility, select "Macintosh HDD" from the sidebar, then click the "Erase" tab.  Reformat it to "Mac OS Extended (Journaled)", rename it whatever you like, then put all your media files back on it.