Put some lilies back in. What it sounds like you have in there now is floating heart. If it has yellow flowers, it might be yellow floating heart. It's not a true water lily. Water lilies will actually take in more nutrients, taking away what is feeding the algae.

Filter the water.. We use quilt batting and the heavy filter media from the fish store.. wrap the heavy filter materal around the pump then wrap quilt batting on the outside of it then pop it in a bucket or basket and change it every other day or so till your pond clears up.. works wonders

Consider a 10% water change over a couple of weeks. I had a very green pond and did a 25% water change, I also added a bunch of plants and put on a small UV which filtered 10% of my water. I think the water change was the biggest one. Don't do more than 10%, depending on what fish you have, they don't like it .. do it over 2-3 weeks.

By removing the plants that shaded the pond you opened up the water to allow sunlight/nutrients for algae growth.

Plant coverage is good :)

Use caution when wrapping batting around a pump. Fibers can get loose and be pulled into the pump, wrapping around the impeller and burning out the motor.