SPIMemory library - Formerly SPIFlash - now supports SPI FRAM as well! :)

Hi,
I am writing a code for w25q16bv flash memory. it had commands to erase the data upto 4Kb, sector erase upto 64Kb and total chip erase. but I only need to erase 256 bytes in a specified location. i tried writing 0xFF by using SPI.transfer(); function but no use. is there any way to resolve this problem?