How to remove duplicate entries in a linked list input?

I am tasked with removing all duplicate entries in the linked list. Assuming the list is ordered from smallest to largest, therefore all I need to do is remove the duplicates next to each other.

For example: If the list contains {1,2,2,2,3,3,4,5,5,5,5,5,6} before calling remove_duplicates(), it should contain{1,2,3,4,5,6} after.

My problem is that my code will print the duplicates as well whenever remove_duplicates() is called. Here is my code:

list.cpp:

#include <iostream>
using namespace std;
#include "list.h"

// on some machines member variables are not automatically initialized to 0
List::List()
{
    m_head = NULL;
    m_length = 0;
}

// delete all Nodes in the list
// since they are dynamically allocated using new, they won't go away
// automatically when the list is deleted
// Rule of thumb: destructor deletes all memory created by member functions
List::~List()
{
    while (m_head)
    {
        Node *tmp = m_head;
        m_head = m_head->m_next;
        delete tmp;
    }
}

// always insert at the front of the list
// Note: this works even in the SPECIAL CASE that the list is empty
void List::insert(int value)
{
    if (!m_head || value < m_head->m_value)
    {
      m_head = new Node(value, m_head);
    }
    else
    {
      Node *ptr = m_head;
      while (ptr->m_next != NULL && value > ptr->m_next->m_value)
      {
        ptr = ptr->m_next;
      }
      ptr->m_next = new Node(value, ptr->m_next);
    }
    m_length++;
}

// iterate through all the Nodes in the list and print each Node
void List::print()
{
    for (Node *ptr = m_head; ptr; ptr = ptr->m_next)
    {
        cout << ptr->m_value << endl;
    }
}

void List::remove_duplicates()
{
    Node *curr = m_head;
    Node *temp = m_head;
    Node *delPtr = NULL;

    if(curr == NULL)
    {
        return;
    }

    if(curr != NULL)
    {

        if(curr -> m_value == curr ->m_next ->m_value)
       {
           delPtr = curr;
           curr = curr -> m_next;
           temp ->m_next = curr;
           delete delPtr;
       }

       else
       {
           curr = curr -> m_next;
       }

    }

    }

list.h:

class List
{
    public:
        List();
        ~List();

        void insert(int value); // insert at beginning of list
        void print(); // print all values in the list
        int length() {return m_length;}
        void remove_duplicates();
        int *convert_to_array(int &size);

    private:
        class Node
        {
            public:
                Node(int value, Node *next)
                {m_value = value; m_next = next;}
                int m_value;
                Node *m_next;
        };
        Node *m_head;
        int m_length;
};

main.cpp:

#include <assert.h>
#include <iostream>
using namespace std;
#include "list.h"

int main()
{
    List list;
    int value;

    // read values and insert them into list
    while (cin >> value)
    {
      list.insert(value);
    }


    cout << "printing original list: \n";
    list.print();

    list.remove_duplicates();
    cout << "printing list after removing duplicates: \n";
    list.print();
}

Note: Everything has been given to me by my instructor, the only code that I am supposed to write is void List::remove_duplicates()

I have looked up other examples on stackoverflow, but none seem to help me with my situation. Also, I do want to mention that I am still very new to Linked Lists and how they function. Therefore I am not exactly sure where to go from here. Any help would be appreciated