Any fronds that are completely brown can be cut off, while those that are still partially green should be left on. Most ferns require high humidity environments, and low humidity can cause browning fronds. Some people place their ferns in the bathroom so they can benefit from the humidity from showers.
There are several other possibilities for why it would be turning brown. I am not sure what species your fern is, but the advice in this article about Boston ferns will apply to most ferns:
https://www.gardeningknowhow.com/houseplants/boston-fern/boston-fern-turning-brown.htm