In VL, a neat trick:
(if (setq e (car (nentsel))) (vla-delete (vlax-ename->vla-object e)))
This will apply the change to all block
references of the block definition relating to the picked block.
If you want the change to apply to a single reference you will need to re-make the block definition with a new name without the object in question. This is better accomplished by copying the block definition (perhaps using my program
here), and then applying the necessary changes, this way, Dynamic blocks would still work.
Lee