my Add button adds 3 rows but I can't get the remove button to remove them.

I have a form with a string of tables - the form needed to repeat 3 rows for various bits of entered data. I needed an Add and a Remove button to add these 3 rows. Instead of making one table with a large number of rows, I created separate 3-row tables.
 
I am able to make the Add button add the proper 3 row sets of the last table, as many times as needed.
 
I cannot figure out how to remove these same row sets.
 
Here is my javascript for the add rows button:
 
// '_' is shorthand for instanceManager, eg '_rowSubform'
_SubformExtra.addInstance(true);
 
// if the edit mode is active, deactivate it
// also want to have new subform in non-edit mode
editRow1.execEvent("click");
editRow2.execEvent("click");
editRow3.execEvent("click");
 
-----
 
Can anyone suggest how the script should look to remove the rows with one click of the button?
 
Do I need to go about creating this whole thing in a different way?
 
Thanks for helping.