I even deleted the old project Folder
in my R Projects dir.
But the old (not needed) Project name (ie: OldProj"),
still appears in the Rstudio Projects dropdown menu (at the top right of the IDE).
How do I (easily) remove that Proj name from the Projects menu?. THKS! 
You can clear the list of projects using the Clear Project List button in that menu, e.g.
Does that help?
(Unfortunately, it's not possible to clear projects one-at-a-time from this list.)
Hi Kevin - thanks for responding,
No, it doesn't help to clear ALL projects
from the Projects menu,
I only need to remove the name of ONE single Project
from the Projects menu.
Hope a "Remove Project Name"
option will be included
in the next version of Rstudio,
Really needed option...thanks 
Hi Sfdude,
You didn't specify what platform you're on.
If you're on Windows you can find the projects MRU in C:\Users\<your user>\AppData\Local\RStudio-Desktop\monitored\lists\project_mru.
If you're on *nix your milage may vary, but on my Ubuntu 16.04LTS you can find the MRU in ~/.rstudio/monitored/lists/project_mru. This is for a local rstudio server installation, but I suspect that a rstudio desktop installation will put the MRU in the same location.
The project_mru file is just a text file that you can edit manually. You don't even have to restart RStudio to see the changes
Cheers
Steen
Thank you Steen
for your clear and complete solution.
It WORKED immediately!!.
Thanks again!