I'm new to elementary os loki, i cant find the way to remove the red dash icon from wingpanel. alt+right click is not working. any suggestions? I have uninstalled Mega.nz app, but the icon place holder is backed up by this dash icon.
I installed Dropbox from the AppCenter and it didn't fly. When I removed it, the red dash sign went with it. It was only after I tried to launch Dropbox and didn't fly that I removed it, so the indicator might be there for something you installed and is not working. I'm a newbie too, but I hope this helps.
I tried to recreate your issue. While I was not able to recreate it, here is what I suggest you try.
sudo apt-get install gnome-software
Then go to the Mega download page and grab the appropriate .deb https://mega.nz/sync
Once that is downloaded, go to your downloads folder and right-click on the mega .deb go to "Open with" then "Software Install" This will reinstall the program through gnome-software.
Once Mega is installed open the program and login. Then close to program Go back to gnome-software find the Mega program Select "remove"
This got rid of the icon in Wingpanel when I tested it.