Can you edit songs to make them simlish yourself?

Is it possible? Yes, maybe..
Is it possible for someone who doesn't has enough knowledge of making music/editting music/mixing music and only using Audacity? No.

Of course I don't know how much you know about mixing music and stuff, but if you don't have a program you bought, then I suppose you aren't a professional.
There are ways in Audacity to somewhat remove the vocals, but it won't work for every song. You can find a lot of those ways on Youtube.

You can probably download karaoke versions of songs. But sing them yourself and turning that into the celeb's voice is probably impossible for the simple reason that probably many more people would be doing that to make illegal money.

You can also try to just play songs backwards, then sounds quite simlish too.

Thanks Bakie !! Whoa you're so helpfull!!
And after I do that how do I change the song to sound simlish?

Thanks!