You may ever see a question mark on your Mac's dock and not know why it appeared. This is something more common than we think and more for those who are testing, installing, removing applications more constantly. In this case what we have to do is "finish" that application or tool that we had previously eliminated and that continues to appear in the system, in this case in the dock.
Now that we have a little more free time thanks to summer and vacations, it is important to do a little cleaning of our Mac and when removing apps this may appear question mark on the dock. So let's see the simple way to remove them from our team.
Yes, it is an app that we have already removed and that continues to appear
Having the app docked in the dock is the most normal thing for this to happen when we delete the app. This app or tool may appear again in our dock although we have it removed from the applications folder of our finder, so what we have to do is finish eliminating it.
Removing the icon is as simple as drag this same icon in the shape of a question mark out of the Dock of our Mac and take it directly to the trash. In this way what we are doing is cleaning the dock of these apps that we had previously eliminated and that when they are anchored in the dock, they remain there as a question mark. In versions prior to macOS Mojave, once we drag out of the dock, the option "Delete" may appear, so we simply release and voila, the app will be eliminated.