I want to start over

my WD drive says it is almost full!  IMPOSSIBLE.  I only have 250 GB on my home drive.  Should be 500 GB on the WD drive, and the WD programs and stuff should not be included in that when it states 500 GB, its like false advertisement.  

I know that half of the “stuff” on the drive is WD stuff I do not need. I’m just not sure what I can remove so that the auto backup will continue to work.  I don’t mind if I have to start over but I just don’t know where to start. Any help?

And why can’t I delete anything when I try to do that?  Drive is not locked but I cannot delete the user manuals.

Follow this link:

formatting the drive will erase the files in the drive.