OK, are you working on multiple tracks or a single track? If multiple tracks, then you really should be using a seperate track for each section.
If you're using a single track, it can get nasty. Zoom in on the area in which the part to cut starts, until it is fine enough to get the right time selected. Place your marker there.
Next, drag the horizontal scroll over to the time in which you want the deletion to end, and press shift+left button at the desired time. Now press the delete key (and confirm deletion). There you have it.
Of course, nothing beats having an unedited backup!
If this doesn't help, let me know what you are doing with more specific detail. I've used Cool Edit since CE95, and still use it today as
Adobe Audition.
