Do you need to do it in a script? if not, a simple find/change will do the trick (in the find format dialog you gave a category called "conditions". select the one nedded and replace with nothing).
if you need to do it in a script, again it's a simple find/change:
app.findTextPreferences=app.changeTextPreferences=null;
app.findTextPreferences.appliedConditions=['NameOfYourCondition']; //notice it's an array
app.activeDocument.changeText();
app.activeDocument.conditions.itemByName('NameOfYourCondition').remove ();