if this is about you having a video jerking in front of a phone then just ignore it.
Also: put a sticker on your camera. Even better if you disable the microphone for privacy too, but that's difficult on phones.
If I'm being blackmailed by somebody who asks me to buy bitcoin and pay it to their account why can I not report this to bitcoin?
If the blackmailers would ask for dollars, would you report this to dollar?
For what it's worth: if it's the standard spam, it's not really blackmail, it's just spam. Ignore it, reporting it to the police isn't going to help you either. Unless it's something personal, but that's not likely.
I'm curious: OP's username looks like they're just using Bitcointalk for spam.
Or they're dumb enough to get more spam on their real email address.