i don't know how to remove the drivers but i reinstalled flashtool:
i removed flashtool - reboot - install flashtool - reboot - installed flashmode and fastboot drivers - reboot- tried to flash = same error.
when i click the flash button the device is not connected. flashtool ask than to connect the device in flashmode ( hold volume down button and connect with the usb cable)
that's when the error occur. at the same time windows tells me, "usb device not recognize". adbdriver tool tells me that the adb driver are installed...
I have the flashtool installed with all the drivers and the adb too. please help.