Your audio has what is technically referred to as "distortion". There is no way to remove it, at least not by any software or hardware that I am familiar with. Maybe an audio engineer with special gear and a lot of time could do it, but not us.
The best that can be done to remove that noise is to give it a steep lowpass filter. SoundForge
has no such filter (at least not in the configuration that is needed). I would Goldwave in this situation.
I would use SoundForge
only to correct other aspects of the file (reducing bass, bringing out the high/mid tones, attempt to restore fidelity).
This is the process I'd use (text only):
Lowpass filter - static, 5000, 20
Graphic EQ - Restore High
Paragraphic EQ - High Restore P (Volt6)
Paragraphic EQ - Remove Bass Grumble (Half)
Lowpass filter - static, 4200, 20
If you want some images to go with this, let me know. Of course this is assuming you have access to Goldwave, or can find a trial that is not crippled (one that is fully functional during a trial time). The goldwave.com site does not make reference to how the trial works.