Unknown app running during shutdown

I have experimented with a number of backup apps that run on windows (10) shutdown - these have been successful. However, I have deleted these apps and cleaned the registry of their trace as far as I can. However, randomly the shutdown process is interrupted by a backup process that fails to complete and the machine reboots (there is text on the screen saying that a backup is taking place) . I would like to have a look at a detailed shutdown log but have found the EventViewer not that helpful - I may need to go through the whole shutdown process line by line. As I have win10 Home I do not have Group Policy Editor that some sites suggest might help. What is the best way of me finding out what processes are called during (my pc's) Shut Down so I can track what this mysterious app/backup process is? Many thanks.

Try running---sfc /scannow---and---dism /online /cleanup-image /restorehealth---to solve any file corruption during the "cleaning" process.
Did you backup the Registry before touching it?
The recommended image programme is Macrium Reflect,paid or free.Excellent.

If you're having hang programs during shutdown process you can use this batch script to close programs that is not responding during shutdown.

The core problem has been ignored!
The OP has removed some unwanted backup programs ... but at least one of them is still running.

@quarrad: Does the shutdown screen tell you what program it is? If so, find the file, find its folder, and delete it.

As to the other question: "What is the best way of me finding out what processes are called during (my pc's) Shut Down so I can track what this mysterious app/backup process is?"

Shutdown does not call other programs. If that unwanted backup program is running during shutdown, then it was already running before shutdown. Find it. Kill it. Delete it.