Sorry my system is down at the moment ( see my post losing video previews) but is ther not a noise gate function in PP that can be used to cut out noise at a certain level.
Me myself I would use a third party app ( I am a cubase user ) and would import all into cubase and manually take out what was not needed. Then save the file with the whole clip adjusted. As Mr H said ther are some good free apps that can help without the expense. But my background is audio.
Gotta dash but my osx has just loaded and I have some debugging to do myself.