1. Make a selection in the wave, taking a part where you can listen only the noise you want to erase. Select a part with no other sound but the noise. Press Effects/Noise Reduction-Restoration/Capture Noise Print. Now Adobe Audition knows what do you want to erase.
2. Select all the wave. Go to Effects/Noise Reduction-Restoration/Noise reduction (process). Press button ‘apply’
3. After that I heard a bit of distortion. I get rid of it using Effects/Filter and EQ/FFT Filter. Values: 20 Hz:-300; 100 Hz:0; 1 khz:0; 20 khz: -300.