The Byte pin needs to tied either to VCC or VSS to configure the device as 1M x 16 or 2M x 8. It cannot be used dynamically.
For your application requirement, i suggest you to use the BHE and BLE pins. These pins can be used to write 16 bits into the memory and read data 8 bits at a time. Please refer to the truth table given in the datasheet to use the memory as per the requirement of your application.