Access parent variables and functions through component c++

I suggest you read a basic C++ object oriented tutorial.
A class member is:

class.... {

    public:  (or private:)


             MySpawnerActor* parentSpawner;  //<-- that's a class member.



}

And inside your c++ you get the instance, wherever you want. in the BeginPlay function, for example:

parentSpawner = (MySpawnerActor*)this->GetOwner();