Ctrl + a works in Windows just like it does in Sonar to "select all"

If you are using Windows there should be a check box toward the top left under name that if checked will select all. I believe this was introduced in Vista. You can then just hit delete.  

this will most likely make your computer run more efficiently too. Temp files are a necessary evil in order to keep your programs running smooth, especially surfing the web, but they ain't called temp files for nothing! with a purge of that much clutter , you may want to let the defragment program take a few passes at the disk once your get rid of them. You will free up a lot of room for files to condense themselves so they run smoother.

I was able to delete the temp files successfully. I had to delete in sections because a couple of times a file was not allowed to be deleted but once I got around that, everything would delete. So I got back my 316Gb of space. Sweet.
Thank you all for your input and help with this. Rick Ranum

MB or GB? 316GB is a lot.
 
Another "trick" you can do is to select that folder and copy (Ctrl-C), then go to the desktop, right click and "Paste Shortcut." This will give you an easily viewable drill-down into that folder. Then you can simply open that shortcut, Ctrl-A (select all), and hit Delete when you happen to think of it. Do not get too anal about deleting everything, since that folder accumulates temp files quickly; just delete what is not locked by another program and you will get most of it.