Cutting Roots ?

[mjgord51]

I have a Phal that I rescued from one of my Daughters. It is about 5 years old and looks like its all roots bound in a 4" X 4.5" container. This one has"Only" been watered and never has been re potted with new potting material.

Now is it possible to "Thin" down the root system by cutting off some of the roots or some that don't look so healthy. I can if needed post a few pictures if needed.