HELP WITH NOISE REMOVAL FEATURE PLEASE

Hello All. Im a bit if a noob to all this but im learning as fast as i can.
 
I have a problem i need help with please.
 
It says that guitar Tracks Pro 4 has a noise removal function where you can take a sample from the track with the noise and it will remove it from the entire track. similar to Audacity by the sound of it..
I cant find anything on this feature and how to use it. Can anyone help please..
 
Thank You