Q: I had installed NumXL using my own credential (non-admin), and now I wish to uninstall it, but when I try to run NumXL uninstaller from "Settings --> Apps", Windows prompt me for administrator's username and password to continue. What should I do?
Answer: To properly uninstall NumXL from your system, we need to run NumXL uninstaller from "Program & Features" in the classic "control panel".
To launch the classic control panel under Windows 10, go to "start menu" on your desktop (left bottom with "Windows logo"), and type "control. 
Now, click on "Control Panel" icon in the search results to launch the App. 
Next, click on "Uninstall" link to locate the NumXL program and commence the uninstall-process.