|i have 4 euonymus that were planted 2 summers ago.(they are about 18|
|This spring has been very hard on many plants. Rather than being quick to cut them back, I would suggest a wait and see approach. It is possible that foliage buds were damaged and so the now-bare portions will releaf out in a month or so once the plants regather their strength.
In the meantime, you can check to see if the branches are still alive. Live wood is flexible and has green inside the bark. Dead wood is dry and brittle, snaps in your hand, and is an off-color usually brown or gray. Begin at the tips and prune off dead wood, stopping when you reach live wood. If necessary, prune a bit more to give a somewhat symmetrical look.
I would still wait to prune though until you are certain that the freezing weather is over. (The remaining dead tips will provide some protection to the lower portion of the plant if there is more cold weather.)