Application processes that were invoked by the Application Builder can conveniently be killed if needed.
To kill all such processes, choose
Build > Kill All
or click the 
button.
To kill just one such process choose
Build > Kill Application
or click the dropdown to the right of the 
button. This raises a menu listing the invoked applications that are still running in the chronological order in which they were invoked. Select one item from the menu to kill that process.
LispWorks IDE User Guide (Unix version) - 25 Nov 2011