Can a write-secured device be erased?
The only way to clear the write security on a XC9500 family device is to erase the device using JTAG.
For the Xilinx JTAG Programmer, select Options->Erase. This will bring up a box that provides a checkbox for "Override Write Protect." Check this option and then erase the device, which will also clear the write-protect.
The HW-130 cannot erase a device that has write-protect enabled.