Tkinter function to clear old canvas and start a fresh "operation"

[Larz60+]

And that works as expected, the canvas gets deleted and the new GUI is being created through Application_Intro call.

Output:
tkinter reference manual (get a copy at: http://reu.cct.lsu.edu/documents/Python_Course/tkinter.pdf ) states:
delete(self, *args)
 |      Delete items identified by all tag or ids contained in ARGS.

delete does not delete the Canvas widget, it only clears it.
if you wish to remove the widget, use destroy

However, it does not stop the code where its left.

This is controlled by your code.
You should not be recreating the widget, unless you first 'destroy' the original.