Eliminating nuisance Instance starts

My GCP app has been abused by some users. To stop their usage I have attempted to eliminate features that can be abused, and have employed firewall rules to block certain users. But bad users continue to try to access my app via certain legacy URLs such as myapp.appspot.com/badroute. Of course, I still want users to use the default URL myapp.appspot.com .

I have altered my code in the following manner, but I am still getting Instances to start from them, and I do not want Instances in such cases. What can I do differently to avoid the bad Instances starting OR is there anything I can do to force such Instances to stop quickly instead of after about 15 minutes?

class Dummy(webapp2.RequestHandler): 

  def get(self):
        logging.info("Dummy:  " )
        self.redirect("/")

app = webapp2.WSGIApplication(
                                     [('/', MainPage),
                                      ('/badroute', Dummy)],debug=True)

(I may be referring to Instances when I should be referring to Requests.)

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