I assume that you're referring to ZigBee modules since you're taking about routers and end devices.
If you're referring to the S2C ZigBee, then you can change the SM parameter from 0 (router) to any of the other sleep modes to make it an end device.
If you're referring to the S2B ZigBee, then no. The radio's firmware must be flashed using XCTU. This can be done through a local serial connection, or over the air.