How to correctly deallocate class member?

Question

Should I use delete overload or del() function or something else to deallocate class member?

class Field
{
private:
    size_t* square = new size_t[5];
public:
    void del()
    {
        delete[] square;
    }
    void operator delete (void* p)
    {
        delete[] reinterpret_cast<Field*>(p)->square;
    }
};
int main()
{
    Field f;

    delete &f; 
    //or
    f.del();
}

Answer 1

You're looking for a destructor:

class Field
{
private:
    size_t* square = new size_t[5];
public:
    ~Field() { delete [] square; }
};

But learn the Rule of Zero and defer instead to a resource managing class:

class Field
{
private:
    std::unique_ptr<size_t[]> square;
public:
    Field() : square(new size_t[5]) { }
};

Which has the benefits of having move semantics already do the right thing, copy semantics already being disabled, and the destructor already managing your resources.