Delete image/blob content to reduce *.mdf file size?
Yes, deleting the unused images will free up space inside your DB files.  To actually reduce the size of those files you will have to SHRINK them after the images have been deleted.  Here's a link to the MS Technet site for this process.  Shrinking the files will most likely introduce internal fragmentation into your tables and indexes.  A thorough REBUILD would be appropriate afterwards.  On a 10GB database, once a year, this shouldn't be an undue burden.