If you really want to get rid of the allocated memory, replace the vector with a new empty one to force it. C++11 has included the vector.shrink_to_fit() method, but it's a request that may not be fulfilled by the implementation.
myFollicle = std::vector<myFollicles::myFolliclesLib>();
You only need to explicitly free raw pointers! Never call the destructor or a delete on an object in a container. Vector, when clearing, removing or erasing, will call the appropriate destructor (not delete) on the objects it contains. If this is a raw pointer, the actual object it points to will not be deleted unless you call delete explicitly. It's however recommended to use a unique_ptr in this case rather than a raw pointer.