This article describes how you can disable autosave in Office 365 for every file with the use of PowerShell.
Some background info on the Autosave feature
If you are using Office 365 and your store your files on OneDrive, OneDrive for Business or SharePoint Online you will see that the new Autosave feature is enabled by default. This options will save your changes to the cloud as you are working. It will also make sure that others that are working on the same document see you changes in seconds.
This feature is only available on Windows for Word, Excel and Powerpoint 2016 for Office 365. The question is, can we turn it off (forever?)
Disable AutoSave for Office 2016 ProPlus
According to Microsoft there is no option to disable AutoSave for all files, you will have to turn it off for every file independently. Not really workable in some cases, but luckily there is an option to disable the autosave feature through the registry.
Run the following PowerShell code to create a new registry subkeys to turn the feature off:
$path = "HKCU:\SOFTWARE\Microsoft\Office\16.0"
Set-ItemProperty -Path $path\Word -Name DontAutoSave -Value 1
Set-ItemProperty -Path $path\Excel -Name DontAutoSave -Value 1
Set-ItemProperty -Path $path\Powerpoint -Name DontAutoSave -Value 1
If you want to restore the feature, simply remove the subkey DontAutoSave in the given path.