Hello,
i would like a shorter list (now im up to 30) and the ability to erase the list at will
thank you
Almost sounds like you are asking for a feature request for a version of Cubase 7 which will never happen because the last versions of CB 7 (7.0.7) and CB 7.5 (7.5.40) were issued long ago.
But… maybe you can try what is suggested in the forum thread link below. Good luck. 
Regards 
While you can’t do this from the recent projects list in Cubase, you can get similar functionality from Windows. To do this you first need to pin Cubase to your Taskbar. Now if you right-click on the Taskbar’s Cubase icon you will see a list of recent projects. Right-clicking on any of the projects lets you remove it from the list, or pin it so stays at the top of the list. One caveat is that in order to get on the list in the first place the project needs to be opened via Windows (e.g. double-clicking the cpr file). Opening from Cubase’s File menu won’t get it on the list because Windows won’t know you did that.
hello, thank you for both answers,
im working on it,
vspa