How do I remove hair algae from my fish tank?

I have a 5-gallon tank that has a betta, a few live plants, and a hiding place that I have had up and running since August, the fish has been in there since September. A few weeks after adding the betta I have had a problem with various types of algae. I had some white hair algae, some green spotting on the walls, and a green/brown colored hair algae. After doing some cleaning and maintenance, I managed to get rid of the white hair and green spots but the green hair algae will not go away.

I keep the light on for 6 hours a day and the tank is not in direct sunlight. I change about 30% of the water every week and change the filter every two weeks or so. I just did a deep clean where I took out all of the decorations and the heater and scraped them off, as well as wiping off all of the leaves of the plants and vacuuming the gravel, and just a week later it appears to be back just as bad as before. It grows a lot on top of the decoration, in a clump in the center of the tank, and on the leaves of the plants, but it is also starting to grow more on the walls and heater.

What steps should I take to remove the problematic algae? The only advice I have received was from my friend who said to remove all of the water and essentially start over with new gravel. Is that something I should be doing at this point? Any help would be appreciated!