If I don't want to remove whole plants, I'll occasionally pinch off the roots.
I also pinch off the roots whenever I transplant them/disturb them. When I first got frogbit, it shed all of it's roots, so I had little decaying strands all over the tank for a couple days. Now I just remove the roots to prevent/avoid that.
They seem to do okay, but I'm not doing it every week or anything.