Follow these step:
1: disable Automatic updates service(Start
Run
type in "Services.msc"(without the
quotes) and Press "ok" , Look for "automatic update" and select
"disable".
2: Go to C:\Windows and select the software distribution to delete
it.
3:Enable back the Automatic updates service(follow Step 1).
Note: You need to turn off the automatic
updates service because it "locks" the software distribution folder
& it is safe to delete them because it just store the Windows
Update File.