Its cyano a bacteria not an algae..
As stated a good siphon then 3 day lights out then siphon up whats left may be all it takes..
Corals/Fish can take that without issue..
There is also a product called Red Slime Remover (and others) that may be used if you want to go to a chemical solution.
I'd suggest starting with the siphon/lights out and see how that works.. Many times thats all you need..
Cyano does seem to come and go in many tanks even with very clean (low nutrient) water. I get a patch or 2 now and then (mostly in the winter actually)..
I just siphon it out when I do water changes and its not an issue..
Its actually a bacteria responsible for life on Earth so I tend to let it do its thing then clean up after it..