Hi Carrie, Kimberly here from landscape-solutions-for-you.
Thank you for asking the question on pruning back your Yew shrub. You can go ahead and prune back your Yew this spring. Spring and fall are the best time of year to prune. I am not sure what climate zone or if your Yew is a standing Yew or a spreading Yew. Go ahead and prune and shape your shrub. Make sure you cut at an angle so you won't damage the plant. After pruning, water on a regular basis and you can also add a little organic mushroom compost to the soil, as well as some mulch or pine straw. The mulch or pine straw will help hold the moisture in. If you need a couple of tips on pruning, you can read the proper pruning page of this website. I hope this has answered your question, and feel free to ask anytime. Best of luck with your Yew plant and have a great day. Thank you again for taking the time to ask about your landscape need.
Kimberly