First make sure the program is not running.
If you see its icon in the system tray, right click on it and choose
Go to Control Panel – Add/Remove Programs, find Active
Desktop Calendar in the list, select it and click Remove.
Finally, you may also need to change your desktop wallpaper.
To do that go to Control Panel – Display – Background,
set new wallpaper image (or set None if you do not want to have
it) and click Apply
If you did not follow the procedure outlined above and tried
to remove/delete/uninstall the program in some other way then
most likely you did not succeed. In that
case it can also happen that the program is no longer listed in the
Add/Remove Programs dialog. To clear things up and finally uninstall
the program you
will have to install it again first, to the same folder as before and
then go through the correct removal process.