Needing something like a Compose key, I downloaded AllChars from SourceForge. I now have an icon on the desktop
(Classic Shell) but the program cannot be accessed. Snapping on the icon produces "A version of the program is already running on your computer. AllChars can only run once per system. Please exit the running instance of AllCharsNS [sic] to use this version." I have no idea how to exit the running version. It does not show up in File Manager. It does not show up in the Start menu. It is not found by "Search." It also does not show up in Control Panel>all control panel items>programs and features, so there is no obvious means of removing it.
I have used AllChars in earlier versions of Windows, and it worked fine. I need to either make it work (preferably) or remove it, and I don't know how to do either.