Slightly off topic, what security software are you using that blocks sevenforums but allows tenforums?
As Helmut and I have both advised to be cautious about the delete, that message stands.
If you click on a folder, then right click what options are you provided?
If you click on a folder then click on the file menu and edit menu (along top) what options are you provided?
Both the link's I provided had basic Window's Highlighting directions. That is, in a large list of items, click on the first item in the list, hold the shift key down and click on last item. Every thing should become highlighted. Then press delete. A faster method is CRTL+A (select all) then delete. A pick and choose method, click on first then hold down crtl key and selectively click on items, then delete.
Of course the nuclear option, which
very well will break Windows Live, find your mail folder in Windows and delete it. Again this may break your ability to use Windows Live. If you use this method delete the folder(s) from recycle bin. Depending on how aggressive you may wish to be after mail is deleted run a product like CCCleaner to wipe free space. This overwrites sectors marked emptied reducing their ability to be recovered. One pass is good, three passes is near impossible to recover. This takes a very very long time on big drives. If you use nuclear option you will have to sign into to web account and delete.
http://www.pcworld.com/article/28935...find-them.html
If you break Windows Live you cannot download it again from MS and I've seen threads where people are having issues re-installing. If you want a good mail client I would recommend Thunderbird.
Ken