If you want to activate or deactivate noise cancelation (or transparency mode) mode through the control center of your iPhone or iPad then follow these instructions written below: Go to the control center of your iPhone. Now there can be two ways, if you are using a face id phone then you will need to swipe down from the top of the screen (in a diagonal manner) and if you are using a phone on a touch id then you will have to do complete opposite that is swipe towards up from the bottom part of the screen.  Now, you will have to hold the volume adjustment button (hold it on the bottom) and you will get the option for the icon of AirPods Pro Then you will see three options there that are of transparency mode, noise cancelation mode, and off. Select the option of your choice, and you are done.