var doc = app.activeDocument; 
 
var all_bookmarks = doc.bookmarks; 
 
for (var b = 0; b< all_bookmarks.length; b++) {   
        bookmark = all_bookmarks[b];       
        bookmark.name = bookmark.name.replace("--", "");   
    } 

var curDoc = app.documents[0]; 
var allBMs = curDoc.bookmarks; 
 
for (var b = 0; b < allBMs.length; b++) {    
  curBM = allBMs[b];        
  curBM.name = curBM.name.replace("--", ""); 
  if (curBM.bookmarks.length > 0) { 
    for (var s = 0; s < curBM.bookmarks.length; s++) { 
      var curSubBM = curBM.bookmarks[s]; 
      curSubBM.name = curBM.name.replace("--", ""); 
    } 
  } 
}