Q: Do i have to subscribe to itunesmatch in order to delete a song thatwas downloaded and should not have been purchased?

You don't have to subscribe, you can hide songs via your computer's iTunes so that they don't show in Purchased for redownloading : http://support.apple.com/kb/HT4919 (with apps and iOS 7 I've been needing to log out and back into my account on my iPad after hiding them on my computer for them to then be hidden on it, not sure if the same applies to music)