Should I explicitly delete structs in C++? [duplicate]

Let's say I have a struct defined as so:

struct Barre {
        int startString;
        int endString;

        Barre() { startString = endString = -1; }
        Barre(int s, int e) : startString(s), endString(e) {}
        bool exists() { return startString > -1; }
        };

I will create an instance of this struct like this, for example:

Barre b = Barre(2, 4);

Let's say I insert this into a std::map<int, Barre> which is a member of a class, with a key of, for example, 3.

If I then create another Barre as above and overwrite the value of the map at key 3 with this new instance of the Barre struct, do I need to explicitly delete the old Barre object that I'm overwriting to prevent memory leaks? Or does it not persist once it is no longer stored in a map in this way?

Thanks for any help.