The CR1 = 1 means that the BP bits are volatile and can be written.
Below is the steps to write to status register.
1. WREN (06h)
2. WRR ( 01h)
3. 0x00 ( value to be written to Status register)
4. CS# must be driven to the logic high state after the eighth, sixteenth, or twenty-fourth bit of data has been latched. If not, the Write Registers (WRR) command is not executed. For status register it has to be after eighth.
Please refer section 9.3.7 " Write Registers " ( page 78) in the datasheet for the WRR command sequence.
If you write 0x00 no sector will be protected. In case if you wish to protect certain section of the memory you need to change the BP bits accordingly. Please refer section 8.3 " Block protection " in the datasheet to determine which part of the memory will be protected depending on the combination of BP bits.