It's also installed as an add-on module with Firefox. Are you running Firefox? If so, check for installed add-ons and you might find it there. If so, just remove it via Firefox's add-on section.
I don't use bit torrents but a Google search brought this up. Apparently, DNA is a program installed with BitTorrent as a way to speed up internet access.
So, either it got installed by BitTorrent (which you don't have) or Firefox (not sure if you have it, but I'm willing to bet you do.)