Is a dynamically allocated 2D array automatically deleted after the program exits?

I am learning about destructors right now because I am making this assignment about matrices (we're supposed to make a Matrix class and overload operators to do Matrix operations and me and the person I am going to mention in the next bit were planning to also make it perform Gauss-Jordan elimination, if this is relevant) which are represented in this assignment through dynamic 2D arrays.

I heard someone talk about using a destructor for the deletion process of the arrays. I started reading about destructors and one of the events that calls a destructors that seemed like the only time a destructor would be used in an application like this was the termination of the program, so I am left kind of confused as to why he'd need a destructor? What's the significance of a destructor in an application like this?