How do I remove Legacy Extensions on Mac for Acronis software?

Thank you for your assistance. So, when Big Sur comes out will it resolve the problem?

Not really. The program won't work in Big Sur.

Acronis needs to update their kernel extension.

Until Big Sur is released, we won't know whether it will just not load it or if it will put up a warning.

How did you uninstall it? Their uninstaller should have removed the kernel extension.

However, you didn’t need to do anything. The warning is in reference to Big Sur which hasn’t been released, yet.

Have you already deleted the application? If not try using the free AppCleaner  Drag the Acorns application onto it, check all of the checkboxes and click on the Remove button. If you use AppCleaner on an app that you have other apps from the same developer like Adobe, you must be extremely careful checking all checkbooks and deleting. Some for those other files may support other apps from the same developer and deleting them can mess them up - Adobe apps is one primary example.

If you've already deleted the app you can download it again from the website, put it in the Applications folder and then drag it onto the AppCleaner app.

I'm not familiar with how to uninstall programs from Mac unless they provide an uninstaller.

Then you are familiar with how to do it. Either you didn't use their uninstaller or it didn't clean up its crud like it is supposed to do.

If an app needs an installer, you should verify exactly what it is going to modify and determine if they provide an uninstaller or clear, easy-to-follow instructions. If they don't, don't install the app.

If you've tried all the normal methods, including looking at any built-in uninstall feature and checked out the app maker's support site for uninstall instructions you can download this free app that will allow you to easily remove any extensions: https://objective-see.com/products/knockknock.html