what happens if destructor is not present?
nothing will happen :) destructors are optional :) they are not required to be present in your code.
destructors are optional... you can use them or not use them.... just in case: they are used to do stuff before deleting an object... like writing by console "destruction >:D!!"
destructor are not necessarily added.... a program can run successfully without using a destructor.
Our world will be safe
memory is not freed
the compiler will not let you create a class