There will be many people very excited about the prospect of upgrading to Windows 10 on the 29th of July.
At the same time there are other users on Windows 7 and 8.1 who do not want any part of the upgrade for a variety of reasons.
Microsoft has confirmed that the new OS, currently in its final stages of development, will be made available for download/install on eligible systems on 29 July 2015.
In preparation for that, back in April, Microsoft released an update (KB3035583) for Windows 7 (Optional) and 8.1 (Recommended) that is called the Get Windows 10 app. It provides the prompt that started appearing on users systems (Windows 7 and 8.1) yesterday and gives you the option to reserve your copy of Windows 10.
But what if you are one of those users with zero interest in the Windows 10 upgrade?
Since KB3035583 was released as an Optional or Recommended update based on your OS it might not be installed if you avoid those types of updates. If that is the case then you have no further action to take.
If however, you did install that update then it can be uninstalled through Windows Update.
Open up Windows Update and click on View update history.
Click on Installed Updates.
In the search box in the upper right corner type in kb3035583. If the update is on your system it will show up in the results.
Click on the KB3035583 entry in the search results and you will be asked if you are sure you want to uninstall it. Click Yes to remove it.
The system may need to be restarted to complete the removal.
If you do not want to see the update any more be sure to hide it by right clicking on the KB3035583 listing in Windows Update and selecting Hide this update.
H/T to @EdBott who clarified the updates status between Windows 7 and 8.1 for me.