It contains some pop in of gas that releases which causes you to cry from the onion.

So, take your knife and cut about 1/3 deep around the diameter of the onion.

Start off with the bottom of the onion and cut in a circle.

DIY Onion Cutting - Remove the bulb from onion to remove gas smell - Onion Cutting Hack

Image by Cooking With Jack Show via YouTube

It should look like a cone shape, and you will see the bulb that is in the center.

Cut from the endpoint down to where the root was.

Then, chop it however you like.

How To Cut Onions Without Crying - Cooking Hacks - Tips and Tricks in The Kitchen

However, some people may say it will be a waste to remove all of that from an onion.

Its a great option or hack to try out if you want to avoid crying.

Learn how to cut onion without crying - Tips and Tricks on How To Cut Onions - Correct Ways To cut Onions