I don't listen to the Beatles either, and so I don't know anything about the witchcraft thing. However, unless there is actual evidence of cadence of demonic chants and/or occultic imagery being displayed by the band (talking about Two Steps From Hell here, not the Beatles), I really doubt that instrumental music is can be occultic.
However, important caveat must be made that if the song DOES have lyrics, listening to the instrumental version is not going to cut you from the evil influence those lyrics might have had - it's not an excuse. You can hear evil music in your mind even if it's not in your ears. Perhaps that's what you were referring to?
We're not talking about that here, though: we're talking about an instrumental band with a strange name. It's like listening to Lindsey Stirling, except it's not her, it's them.
Also, for the record (pun not intended), people make conspiracy theories up all of the time that aren't true, and the Beatles thing really sounds like that to me.
Anyway, I'd like to mention a book called Fear No Evil by Steve Russo.
If you're really interested in what is actually a demonic influence and what is not, that book is good. Plus, Steve is a drummer, and he has a huge section talking about music, specifically, if you're really worried about it.(I got to meet him when I was younger - it was embarrassing. I did get to see him perform - I will vouch for his drumming skills and spiritual character.)
Anyway, this keeps coming up over and over again about the devil being out to get us, so maybe some clarity on the subject might help?