Sunflower got blown in half - should I prune it out?

I have a container full of Sunflowers out front. The container is a very large small-tree type container, except that I planted Park's Sunflower Van Gough mix in it.
They are staked and caged, still, the wind managed to blow and snap the top half off of one of the real big ones that hasn't bloomed yet.
My question is, since I am a second year gardener and not familiar with sunflower habits... should I snap the bottom half of the plant off at the base of the soil for more water/fertilizer for the other sunflowers, or should I keep the bottom half there? Will it send up a side bud to compensate?
I don't see any other buds except the top one (that got blown off) on this particular plant. For now I put some pruning sealer on it.
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