I agree that deleting fields when they are shared across types will have unintended consequences. But in GraphQL world all the predicates are appended with their types (eg. Test.marks, Test.name); deleting Test should delete Test.marks and Test.name from the list of predicates.
Similarly deleting Test.marks should update type Test.
Thoughts? @pawan @abhimanyusinghgaur @martinmr
Also, I think this is not straightforward to do, I am wondering if some actual query/application was failing because of this @akashjain971?