What variety/varieties are these six hydrangeas? That will be essential for gauging the "regrowth" potential and where to cut.

All it says on the tag I have left is Hydrangea macrophylla. They all look like the traditional hydrangeas and are blue, pink, pink/purple in color. Im sorry that I don't know more. I seriously doubt that they are endless summers though. I have pictures but I am not sure how to load this on this website...

If not remontant types, blooming is probably done for this season. You can cut off the dead flowerheads (deadheading) by cutting back to the next leaf node.

FWIW, in areas with long growing seasons, sometimes even non-remontant (reblooming) hydrangeas will produce new flowers on current growth. No guarantees but it can happen. I'd not expect it on greenhouse-forced plants, however.

Thanks! So if I was going to hope (since its still early in the season) that my hydrangeas would produce new flowers, then deadheading is how I would encourage this versus leaving them how they are?

Deadheading will not make a difference one way or the other in encouraging new blooms :-) With hydrangeas, deadheading is only cosmetic.