If you no longer need a custom application, you can remove it.
Open the Application Wizard pane in System Preferences and click Applications.
Select one or more applications in the list.
To select applications that are next to each other (contiguous) in the list, press the Shift key and then click the first and last application; to select applications that are not next to each other in the list, press the Command key and then click each application.
Click the Remove (-) button at the bottom of the list or press the Delete key.