You will want to cut back the spent bloom stems but I don't think you want to cut back the entire plant. Just provide ample water for a week or so until they get established. There's some great info on the link below. Check the topic Maintenance.

Here is a link that might be useful: Caring for Your Echinacea

I know someone who cuts theirs back every spring so they will bloom shorter and a little later. The groundhog did this for me this year in one of my patches and I'm actually glad since it's towards the front of the garden bed. They are very resilient plants and just need extra watering when first planted.

I would leave them be... unless they don't have much basal leaf growth. I saw at lowes they had a tone of white swan quart pots of echinacea, but they just look like you took a single flower stem and stuck it in the ground. I would cut this type back.

i disbud mine in the spring by pinching the single bud out, right when you can see it formed, this gives me a swirl/whorl of flowers and small new stalks around the main stem, i would just take off all the flowers and leave the stems alone and see if you get another flush of buds down the stem.
the disbudding is a growers trick on mums, you pitch out/take the center bud out to get a new whorl of buds or if it's a bunch of buds and you only want one single you take all the buds off and leave the center bud on, how did i get to talking about disbudding holly

I had a rabbit cut mine back for me once the length of the flower stem and it never came back.

I had a mailman who was snapping off flower buds every day on his way past them in the front garden. (g) It was a mystery how that was happening. I kept finding one or two flower buds on the ground every day with no foliage disturbed. I thought it couldn't be an animal. The mailman was the only non family member who had come to the front door in that time period, so I got up early to watch the mailman one morning and sure enough it was him! He was unconsciously doing it. I found it pretty funny when I saw him doing it. I learned a great lesson from that though, because as fast as he would snap them off, the plant would put out new flower buds. That particular plant had 3x more flowers on it that year then any of the others.