Flushing... hmm... That's an interesting concept. First, are we discussing flushing it finishing? Flushing would be pouring huge amounts of water through your pots to, hopefully, remove salt build up from over fertilization. Finishing would be giving the plant water only the last couple of weeks to, again hopefully, encourage plant death, AKA senescence.
At this point, you would be best off just leaving them alone. The plants are clearly entering the end of the cycle. The first picture looks like it has some time to go, the second picture looks ready. Notice how on the second plant the pistils (white hairs) have receeded and the cylax have swelled? The other one will do that too if you wait for it.
I would harvest the second plant, the. Just give plain water to the first one for a other week. There is no reason you can't start some seeds or clones for next round while she's finishing up.