How to stop Mac App Store from downloading macOS Sierra? Today I've updated my 2011 15" MacBook Pro to macOS Sierra. After everything got updated, I've entered the Mac App Store in order to download Xcode. I saw in the "Apps Made by Apple" section the macOS Sierra, which seemed weird to be shown as downloadable, since I've already downloaded and installed it on my MacBook.
I thought maybe it's a minor update, so I clicked on Download button.

Since then, it is downloading the full macOS Sierra. The problem is that I can't stop it. I don't see it in the Purchases tab and on the button where it said Download earlier, it's says now "Downloading". When I press on the option key to cancel the download nothing happens.

Can you please help me to stop the macOS Sierra download? It is slowing the whole Wi-Fi...
Even though you already installed macOS Sierra, App Store still allows you to download the original install file.

There are 3 methods to cancel a download in Mac App Store:


You can stop the download by going to Launchpad, click and hold on macOS Sierra and click the small 'x' button to delete it. This will stop its download.
Turn off your WiFi temporarily and Mac App Store will show a message that the download has failed. Then, find the downloaded file in the Applications folder and move it to Trash. Empty the trash and turn your WiFi back on.
Go to the Purchases page in Mac App Store, hold down option key and click Cancel. The download will be cancelled.