Unable to delete Comments in Acrobat ProDC Shared document

There are Action Wizard tasks for deleting highlights from PDFs.  If you go into Action Wizard, make a New Action.  Go to more tools and then select 'Execute JavaScripts' and click the plus sign.  Then on the right side click 'Specify Settings' and paste the code below into the box.  Uncheck the 'Prompt User' setting.  Click save and give the command a name like "Delete All Comments", and click save once more.  Then run the command from the 'Actions List'.  You will be prompted to proceed as this action cannot be undone.  

/* Put script title here */

if( app.alert({
cMsg: "Are you REALLY, sure you want to remove all annotations, comments, and markups from this PDF?\n\nClicking 'OK' will remove all annotation, comments, and markups and save (overwrite) the existing file.  If you want to save the comments in this file, click 'Cancel' and save your changes under a different file name.\n\n\tThis action cannot be undone.", // 2nd message to display
cTitle: "DELETE ALL ANNOTATIONS", // title for pop-up box
nIcon: 2, // question icon
nType: 2 // yes/no buttons
}) == 4) {

this.syncAnnotScan();
var tObj = app.thermometer;
var annots = this.getAnnots();
tObj.duration = annots.length;
tObj.begin();



//DELETE ANNOTATIONS////////////////////////////
if (annots!=null){


for (var i=annots.length-1; i>=0; i--) {

tObj.value=i;
tObj.text ="Remaining comments: " + i + " of " + annots.length;
annots[i].destroy();


}
tObj.text = ""
tObj.end();
}

}

Any resolution to this?  I have a bunch of PDFs that have hundreds of comments created by AutoCAD.  Trying to delete them but the delete button is greyed out just like in the op's comment.

Just for the sake of trying, select some comments in your Comments Panel, and right-click.  Is there a Delete option showing with this technique?

Also, do you have the capability to open that same PDF on another machine?  WOuld be interesting to isolate if it is that document, or that installation creating your issue.

My best,

Dave