Nah, its not a lighting issue.
You can remove the substrate slowly if you would like. You want to suck it out with water changes. Personally I would remove it all in say 6 stages before adding any sand.
Before dosing chemiclean you need to solve the nutrient source. If you don't the bacteria will just come back. Cyano is one of the easier issues to solve and sometimes it just takes time.
If you notice the cyano is really only covering the substrate. Your rock has some turf algae as well.
The rock is going to have bound phosphates that will leach over time. GFO is a great tool to remove those nutrients. Removing the substrate, running a little gfo for a few weeks changing it every couple days, confirm you have zero tds source water, and then dosing chemiclean as per instructions will get you a long way in a short period of time. If you are in it for the long haul you should realize this doesn't have to happen overnight. It won't happen overnight.
Don't add more clean up crew unless you absolutely have too for now.