If the leaves are dead, then there's no point in leaving them, so yes, cut them off.
One possibility is fertilizer burn. On cycads, new leaves are particularly susceptible to fertilizer burn. IF you have recently fertilized, I bet this is the case. Nothing to do except wait, and maybe give the surrounding soil a good, deep watering or two to help flush out some of the salts. But don't overdo the water, as sagos don't enjoy wet conditions.