linked list - elements come after removeing

I have a Node class to implement linked list:

class Node
{
    public:
        int data;
        Node *next;
        Node(int d){
            data=d;
            next=NULL;
        }
};

And in a solution class I have methods to insert, removeDuplicates, print etc;

Now to removeDuplicates my logic is:

• if my current's next node is null then return
• if current's value is equal to current's next's value then set next to current
• recurse with next

So here is my code:

Node* removeDuplicates(Node* head)
        {
            process(head);
            return head;
        }

        void process(Node* node)
        {
            cout << node->data << endl;
            if(node->next==NULL)
                return;
            if(node->data==node->next->data)
                node=node->next;
            process(node->next);
        }

when I call removeDuplicate method, it prints: 1 2 3 4 as expected, but after that when I again print with my another method, it gives me the whole linked list, without removing duplicates : 1 2 2 3 3 4

display method:

void display(Node *head)
          {
                  Node *start=head;
                    while(start)
                    {
                        cout<<start->data<<" ";
                        start=start->next;
                    }
           }