Yes, you can. Google images of conifer hedges for examples. It's done all the time. But you'll need to do it at least annually for ever.

A general rule of thumb on a multitude of evergreens is that you can prune into the green foliage, but not into the woody portions as many of them won't sprout new growth from them. Therefore, it's important to keep up with the trimming so you aren't forced into the wood-only portions. It looks like now you could easily level it off while remaining in in the portions that have vegetation.