Getting rid of typing sound

Hi,
How do you remove typing sound (tapping sound) after you have recorded your movie (without getting rid of showing typing)?

My probelm is related to importing actually.
When I recorded my movie in movie1, I have the hear tapping unselected and I cannot hear any typing sound when I preview the movie.
I had another movie2 created as blank presentation and with powerpoint slides imoprted. Then I import the recording slides from movie1. Now those slides that I imoprted from movie1, when I preview in movie2 , I can hear the tapping sound. I found no way to delete it. The audio screen shows no audio.

Thanks in advance.