I inherited a large, 18" pot, peace lily that was near death. 5 months later, 20 new stocks, about to bloom and looking very Healthy except for the original stocks. Is it best to just cut the older stocks out that are damaged & give all the energy to the new growth.?? It would look visually better yet unsure if it's best for the plant overall..? Your experience is appreciated.

Yes, its OK to cut the damaged stocks, its better for the plant, use clean scissors or pruners.
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Either way, it will have no effect on the rest of the plant. It is an aesthetic choice and most people would agree that it looks better with dead plant tissue removed.

Be sure to take a close look at what you're cutting before you cut it! Sometimes, those leftovers can look dead but the lower part of the stem can actually contain a new leaf that hasn't emerged yet. I find that cutting off dead leaves but leaving the stem until I'm sure it won't bring forth a new leaf works best. Once that new leaf emerges, you can cut the dead stem away.

And yes, !