Type adb reboot bootloader . The phone will restart into a special screen (fastboot mode). Unlock: Type fastboot flashing unlock . Note: On older devices, use fastboot oem unlock .
Follows the standard ADB/Fastboot method above. unlock-tool-loader
Requires the Mi Unlock Tool and a bound Mi Account, often with a waiting period. Type adb reboot bootloader
Type adb devices . If authorized, your device serial number will appear. unlock-tool-loader
This will help me give you specific commands for your unlock tool.
Go to Settings > System > Developer Options and enable OEM unlocking .