Hi @khan_yas,
I'm not aware of any way to disable a notification like that. The notifications generally provide some transparency to students about changes happening in their courses, and a quiz regrade is likely something students are going to want to know about. The only way I know those notifications wouldn't be sent is if the grading policy for the quiz/course was set to manual and the original grades were never posted. That would all have to be set up that way beforehand though, and it's very important to know that grades will eventually have to be posted manually when using that method, which is the teacher(s) neglect to do, will directly impact student's ability to see an accurate grade for their course.
Hope this helps a bit!
-Chris
