When I delete email from my sent items, or any other view, Gmail asks for my confirmation to delete mail.
Is there any way to I can turn this confirmation off?
Any browser add-on (Greasemonkey script will do)?
NO. There are no such option available in Gmail or in Gmail Labs . None of the popular Gmail Greasemonkey scripts claim to do this. The best you can do is write your own Greasemonkey script for this or suggest a Gmail Labs feature request here. If it's a popular request it might get implemented.