This is very easy tutorial for beginners which is easy to follow Photoshop Tutorial, easy make a partial black and white effect in photoshop.
i Use This Image.
Step 1:Choose Your Any Image Duplicate Layer
duplicate layer Right Click Layer keyboard shortcut key Ctrl+j
and Hide the Copy Layer
select Background Layer
Step 2: Go Image Menu>choose Adjustments>choose Black & White
Black & White Adjustment
Then you have black & white image
Show the hide Layer
Step 3:Select Eraser Tool
And Apply The Area
Here We Are Result