Personally, I strongly urge you to abandon SimpleSave now while you can still back up your data to another destination.
As of a while ago (a few years now), only a very few of us supported this software. I have since stopped doing so the the extent that I no longer provide a personal archive of the software and files. Truth be told, my notes on the subject are mostly gone by now.
Run Away! Run Away!
The software is not supported and, indeed, the software has not been supported for quite a while.
The software was never supported in Windows 10,
The data is encrypted when it is backed up using the SimpleSave software.
When (not if) the software stops working or the disk drive fails, you will not be able to recover the data.
That said, the following is a relatively enlightening thread on the subject that includes a simple "Delete" method.
Side Bar At this writing...
Interestingly, the provided link to the software (near the bottom of the thread) still works. If you are determined to keep using the software, consider downloading the software into a safe location -- SCAN the downloaded file with your security software before using it and / or letting it loose in your File System (just common sense).