If you're absolutely sure that you want to delete them, then......
The first thing you'll likely have to do is "Take Ownership" a link and brief explanation to a handy utility that will help you do this is included in this article here Link Removed
After that is done you may be able to delete them. If not.....
Right click the item, choose properties, select the security tab and add the "everyone" group and grant that group "full access". You may also need to disable inheritance so as not to have troublesome permissions passed down from the parent container.