Yes, Wavepad is an audio utility. Here's what the HELP file says about de-essing...
"We do not have any tools in WavePad specifically for de-essing or de-breathing.
We suggest using the Equalizer or the Dynamic Range Compressor. You can access both of them from the Effects tab toolbar.
Another option is to get a third-party VST plugin, then use it with WavePad's VST plugin support (only available with Windows)."
Look here... http://www.best-free...de-esser-01.php
And search for others. Also check in to the Wavepad forum.