Destructor explicit calling

In fallowing code , why p.destroy() ; is called with(.), why p->destroy() ; not used.

class Nonlocal {
    public:
    // ...
    void destroy() { this−> ̃Nonlocal(); }
    private:
    // ...
                 ̃ Nonlocal(); // destructor

    };
    // explicit destruction
    // don’t destroy implicitly
    void user()
    {
    Nonlocal x;    // error : cannot destroy a Nonloca
    X∗ p = new Nonlocal;  // OK
    // ...
    delete p;   // error : cannot destroy a Nonlocal
    p.destroy();      // OK
    }