It looks like Annabelle to me. Does it have blooms that start white and turn green (as they look in your picture)? Annabelle is very winter hardy and a reliable bloomer. It can get 6' wide in some places. It has big blooms but the stems can be weak. The stems sometimes bend when the blooms get wet.

You could rejuvenate the shrub by pruning 1/3 of the oldest stems all the way to the crown in late winter, prune the next third a year later and prune the rest in two years. Annabelle can be pruned at almost any time of the year (not when it is about to bloom so you can enjoy the blooms).

I have not tried to kill one so no comments there but, you could transplant it or offer it to gardening clubs who have fall sales to raise cash.

Luis

Yes it does turn green so I assume it's Annaballe. Although I've tried to keep it in check it has expanded to an area of about 10' X 15'. I wound up cutting it down and grubbed a 4' diameter hole which took several hours in which I planted a newly purchased H. Limelight. I planted grass seed in the remaining disturbed area in hopes that the grass will grow and I can eventually kill off the Annabelle roots with the lawnmower. If not, I'll have to resort to herbicides.
Thanks for your response.
John

You're welcome. The original single shrub could have propagated via suckers that, given enough time, became two or more large (wide) multi-plant shrubs.