Go to Business Manager.
Click on the drop down menu in upper left corner and click “Pixels.”
Click on the name of the pixel you want to stop tracking.
Click on the Ad Account of the pixel you want to stop tracking.
Click the gray “X” to the right of screen.
There is no way to delete a pixel from a business manager account, you can only stop it from collecting data.
I recommend you to use the same pixel in Shopify that is used in the Facebook ad account or you can create a new pixel by another name so that it's easy for you to recognize.