How to unicast the data from coordinator to router in AT mode?

Hello everyone, I’m using 3 xbee’s S2c firmware is XB24C-Zigbee TH Reg-4060 to create a tree network, in which they are configure as 1 is coordinator and rest 2 are router in AT mode and using XCTU console to view the data and configure the Xbee’s.

I want to know, how to transmit the data from coordinator to single router in AT mode?