Hi Thhm,
Give what’s suggested in this post a try → How do I delete projects? - #9 by tmek
Edit: You might actually have better luck with this ‘fix’ Remove Project From Launcher Without Deleting - #6 by Appifiny_Solutions
In 5.x the folder you’ll find EditorSettings.ini in is now called ‘WindowsEditor’ instead of just ‘Windows’
Let us know if that method still works!
~
Another way to distinguish the ‘same project’ in different locations is by dropping an icon ( 192x192 PNG works for me) into the base folder (Next to the .uproject and with the same name as the .uproject)
Cheers!