How to convert video to black & white or grayscale mode- Handbrake tutorial

http://bit.ly/2vMdPqK MakeMkv free download page.
I dont know whether anyone in need of this tutorial or not, but I thought it may be helpful in some case. Hence here it is - How to convert a video ( in this case mp4) to black & white / grayscale mode using handbrake. Note - In handbrake output mode will be either mp4 or mkv only.