Take Full Backup of your phone, contacts, SMS and all your internal storage files.
1. Settings-> About Phone-> click 5 times on MIUI version - This will enable developer options.
2. Settings-> Additional Settings > Developer Options > Mi Unlock Status -> add account here
If you get any error, logout your mi account and login again and repeat step 2.
3. Settings-> Additional Settings > Developer Options > Check on OEM unlocking
4. Install adb driver. - > https://forum.xda-developers.com/sho....php?t=2588979
5. Download MiFlash unlock > https://en.miui.com/unlock/download_en.html
6. Boot Redmi 6 pro to fastboot mode (Power off > wait 5 sec > Press Vol Down - > Power on)
7. Run MiFlash Unlock (Run as Administrator).
8. Sign in the same account which is logged in this device.
9. Unlock (This will erase all your data, Everything on Internal storage)
10. After unlock, Device will reboot.
11. Complete the setup, If you have find my device ON it will ask the password
12. Boot Redmi 6 pro to fastboot mode (Power off > wait 5 sec > Press Vol Down - > Power on)
13. Download TWRP Image. and copy image to adb folder -> https://dl.twrp.me/sakura/
14. Download this zip - https://forum.xda-developers.com/att...2&d=1540504900
15. Thanx to mtk_xda for above attachment.
16. Run cmd (Run as Administrator).
17. Use this command to boot the image > fastboot boot twrp-sakura.img
18. Wipe/Formats Data.
19. Install Disable-Force-Encryption-TWRP-flashable-zip-TREBLE.zip
20. Reboot to Recovery.
21. Reboot to System. - Done
I have just unlocked the device without any wait and wrote the all the steps.
PS : I have installed my favorite font via twrp