Mine are looking pretty shabby after the harsh winter. Can I just cut the top portion off and it begin to produce leaves again, providing it is still alive?
Yuccas respond well to pruning. This article talks about indoor yucca, but pruning outdoor plants is the same. https://www.gardeningknowhow.com/ornamental/foliage/yucca/yucca-plants-care-and-pruning-tips-for-pruning-a-yucca.htm
Go ahead and cut off the yellow leaves and cut the top down as far as you want.