You could take a net and go back and forth until you have it all off. If this doesn't work you could take a piece of paper/cloth and drag it across the top of the water. You could increase the turbulence at the top of the tank with an airstone/curtain. Possibly cut back on some feeding. HTH
You need to break the surface of the water with either your filter or a bubble stone/wall. It's very important for oxygenating the water and for not getting the film you had.