help,.. huawei y300-0151 read only…

hi, i want to unlock bootloader of this unit huawei y300-0151. i want to flash via sd card update because its infected by viruses…but error happen it says "read only".. as i read along, it needs to be bootloader unlock to be able to flash firmware,..

i try this via fastboot,.

how to enable the menu just like in my screen shot..?