How can I make the compilation to achieve MEMORY using RAM but not LEs?

The Edit menu is context sensitive, so it will only be there if you have a VHDL file open in the main window. If you're looking at a compilation report or something like that it won't be there. (Or you're using an older version of Quartus, but I'm pretty sure these are at least a year or two old). And using the code from the referenced manual will also work.