I personally wouldn't take everything out. A small amount of algae is beneficial to your fish and snails. I would get a common pleco and he should clean up youth sides and a slight layer of algae on your plants and decor in a matter of days. However with the size of tank you have, a pleco will grow out of and you may need to replace him with a smaller one later on. If you don't want to buy another fish though you can scrub the sides of the tank, the decor, and plants inside the tank while it still contains your original water and fishes (it is very stressful on your fish to remove them everytime, however if it is excessively dirty This time i would remove them but in the future its not ideal). Siphon around 30-50% water out of the tank and brush through the rocks with the siphon tube. I would then take a bucket and fill it up with water equivalent to what you just removed. Then add your chemicals (aquasafe, algae control formula, salt, etc.) and be sure to add the specific amount only for how many gallons you have just removed, stir it well. Id let that sit for a couple minutes (10-15) then slowly add it to your tank.
Your tank will be a little foggy for maybe a few days at the most if your tank was quite dirty.
If you do this once a week with around 20-30% water change your tank will progressively become clearer and cleaner. However the first couple of times will be a bit nasty if you haven't been doing PWC's (partial water changes) frequently in the past.