siphon it off (or lift it if it's a solid mat) if you can. If you can't siphon it you can blast it off with a turkey baster.
People used to think that blasting it would spread it but it's right in between bacteria and algae and can get anywhere anyway. Blasting it apart does two things:
* it takes energy for it to restructure
and
* lets biological filtration takes place again where the cyano previously prevented that by covering it. (I just read in a Goermann book that once established it actually takes very little nutrients in the surrounding water to sustain it because it covers existing bio filtration)

After your blasting work you can siphon it easier. Do your water changes after your blast work and you are good to go.
If you do it in the evening the air bubbles from the day's photosynthesis might even help it float up while you blast.

Soon enough people will suggest some quick fixes and I just wanted to share what I learned about the different options:
- old style slime removers with antibiotics can negatively affect your biological filtration
- newer style oxidizers (like Chemiclean) work fast, but oxidizers can also harm fish gills. Follow instructions carefully
- Zeo system style enzymes work slowly but appear to be safer. Zeo stuff is also expensive

I am not brave enough for options 1 and 2 but I am trying option 3 right now.
It still requires water changes but it definitely helps.

My blue leg hermit crabs (C. tricolor) also do a great job eating the rocks clean off the cyano so I have less blasting to do.