@Das67 @michel_hammamet Just to be on the safe side, call the CIC to confirm that you can modify/redo a page of an already signed form. I know that the call centre agents do sometimes give different answers based on their interpretations on the operation manual, but for basic/common stuff like this, hopefully, they have a standardized response.
On the encouraging side: notice that the "CIC Received" stamp is intact and not "vandalized" by that "MP" agent, and s/he did ask you to keep the original "signing date" for the physical presence time calculation. Hopefully, once they deem your application complete, the original "Received" date is honoured to keep your position in the queue.