How to remove icon of uninstalled app?
the standard places where *.desktop-Files are stored are:
/usr/share/applications/ and
~/.local/share/applications/
To check if there is an ark in these folders I'd in a Terminal (Ctrl+Alt+t) do a:
ls -la /usr/share/applications/ | grep -i 'ark' and
ls -la ~/.local/share/applications/ | grep -i 'ark'
if so I'd delete it with sudo rm <pathtofile>/<*.desktop-file>, sudo is not necessary when deleting the file in your home folder.
Afterwards, or even if there is no arc*.desktop-File I'd do a forced update to my menu via:
sudo xdg-desktop-menu forceupdate --mode system