I use AVG, the free version. I have used it for 6 years now, and swear by it. So simple. It speeds up your computer, scans daily without you having to tell it to, deletes viruses automatically. Go to their website for a download. Don't use anything else, everything else is horrid compared to AVG. Hope this helped!!
Deleting programs, to do this go to your control panel (this is on a windows version)
and select add or remove programs, from their you pick the ones you don't want and remove them. The process of uninstalling will take a bit but just be patient with it.
As for pornography, if its on a browser, then going to the history and erasing everything on their usually does the trick. If you downloaded something delete it then check your recycling bin and delete it their.
Also other things you might want to delete are microsoft word documents that you no longer use/need, ancient files that you have never even looked at, programs that have never been touched, photos that have never been used. Basically stuff that if it were physical, would most likely end up on a dusty shelf.
you should download CCleaner!
it works like a charm
and its free
download CCleaner it's free download, it cleans several different browsers and is a registry cleaner too.