Install and open your audio editing program. You can do this by double-clicking the application icon.
Drag the audio file you would like to edit into the application. This will import your audio and prepare it for editing. Some applications might require that you use the "File" menu and select the "Import" option. In that case, select "Import" and browse the file on your computer. Then select the file and press "OK" to import the file.
Highlight a few seconds of pure noise from the audio file by clicking, holding the mouse down, then dragging your cursor over the noise in the audio track.
Select "Get Noise Profile" from the "Effects" menu. This will analyze the noise and close the dialog box. Then open the "Get Noise Profile" option again and click "OK."
Choose the "High Pass Filter" from the "Effects" menu. In the "Cutoff frequency" box, type in the number "65." This will remove most hissing, which occurs at frequencies below 65 hertz. If 65 hertz doesn't remove the hissing, continue to increase the value by 15 hertz until the hissing is removed.