How can I abort Mojave installation? I am on Sierra now, and the appstore has downloaded the Mojave Installer, however I quit it without going though any of the steps, the installer is just sitting in my apps folder.

I would like to cancel the Mojave installation and remove the downloaded files, is there anything I can do?
You already canceled it by quitting the installer, just delete the  installer if you do not ever want to upgrade, or keep it for a later install.

The /Applications/Install macOS Mojave.app can be double-clicked to restart the upgrade, whenever you want.



On a side note, if you do not want the App Store to do things automatically... then in System Preferences > App Store, uncheck the appropriate check boxes.

On my system I like to manually control when any upgrading occurs so I set my App Store preferences as in the image below.