It looks like the cyano I had in a previous tank. I used to let it grow into mats like you have to make removal easy. Once it has formed a mat, it can be peeled off and removed as a single lump. Just ease it off one side of the rock and slide your fingers under. Once you try to lift it out of the water though it will breakup. Lift it to a net under water, or into a small container to remove it from the tank.
People suggest more flow, less flow, more light, less light..... changing these never helped me and the advice I found contradictory. A reduction in nutrients would be my recommendation. Feed less, add a macro to compete, do more water changes. If you can, without impacting other livestock, turn your lights off for a few days to kill it.
Also, are your bulbs old? The spectrum shift on older bulbs has been suggested to contribute to nuisance algae.
If it becomes a real problem, chemicals can be used. I found chemicals to be a short term solution and the algae returned. Once killed by the chemicals, my cleanup crew ate it. They wouldn't touch it while alive.
How old is the tank? If it is still young, patience maybe all you need to clear it up
Hope some of this helps.