I want to delete sofware discarded by Mountain Lion but I can not find the file Incompatible software
It's moved to a folder called "Incompatible software". Search for that name in Finder.
Here's a reference document: http://support.apple.com/kb/HT3258
One more thought: It could be that "incompatible software" is up at the system level.
If you don't find it with the finder search, you may have to do a Go > Enclosing Folder as many as 2 times from Finder's menu.
Macintosh HD > Incompatible Software
Not very well hidden, at least on my MBA.
Retrieving data ...