Assuming this is the aquarium in your log photos, yes, you want to remove the blue completely and not mix something with it.
This is not difficult, and can be done one of two ways. You can leave the fish in the tank and just remove the existing gravel and carefully pour in the new; some do it this way, though I don't like to. I prefer having an empty tank to work in so I can arrange things without worrying about fish, plus without water it is easier to arrange the substrate, plant the plants, then fill and have less cloudiness.
A spare tank with water from the existing tank, plus the filter & heater moved over to the spare, and the fish netted out and into the spare. Then you can take your time to reset the main tank.
Dark substrates are best, both for fish (less stress=better health) and plants (visual, they look nice with a dark substrate and background). This is a 29g so not too large to make a plant substrate like Eco-complete or Flourite possible, but plant small-grain gravel or sand will also work. Just make sure it is dark, whether black, dark brown or gray, or natural.
Once the substrate and plants are in, fill and add water conditioner, then move the filter and heater back and the fish. Don't wash the plants or any decor, or filter; plenty of bacteria will have colonized these, plus the plants assimilate ammonia greedily.