Santa Fe, Texas – My Sago is about 4-5 years old. This last winter seem to affect it pretty bad. The center flower is huge but
the fronds are yellowing. How can I prune it now?
You will have to let this recover on its own. Do not prune anything off that is not completely dead. It will be unsightly, but these are pretty sensitive to pruning. I would wait until the leaf is completely desiccated to remove it.
This article will give you more information on the care of these: https://www.gardeningknowhow.com/ornamental/trees/sago-palm/sago-palm-outdoor-care.htm