You can't delete feedback left for you and the feedback you have left for others is all too old to delete.
If you don't want people to see your feedback, as long as you don't have items listed for sale, you can make your feedback private.
"There are two ways to be fooled. One is to believe what isn't true; the other is to refuse to believe what is true.”
Søren Kierkegaard, Danish philosopher (1813 - 1855)
