I have a java fern that sometimes gets a few spots like those, but not nearly as many. I wouldn't trim off the leaves, maybe just the worst one, if you must, but from the photo it looks like you'd be cutting it down to a stump. give it a few weeks to settle in, watch for root growth and new plants. I'd seperate new plants off and tie them somewhere else, maybe higher in the tank closer to light, to encourage more growth.
thats my pic.. lol
The OP didnt post a pic yet :silly: