如何删除双链表的第一个节点

我有一个双向链表的实现，并且我试图删除给定位置的特定节点。我设法将第二个节点删除到最后一个节点，但是当我尝试删除第一个节点失败时，我想知道我的代码出了什么问题。 head.next.previous = null; head = head.next; 这是我的代码

public class Proses { private class Node{ String Matkul; int NilaiUts; int NilaiUAS; Node previous;
Node next;

    public Node(String Matkul, int Nilai, int NilaiUAS) {
        this.Matkul = Matkul;
        this.NilaiUts = Nilai;
        this.NilaiUAS = NilaiUAS;
    }  
}  

Node head, tail = null;    
public void addNode(String matkul, int Nilai, int NilaiUAS) {   
    Node newNode = new Node(matkul, Nilai, NilaiUAS);   
    if(head == null) {   
        head = tail = newNode;    
        head.previous = null;  
        tail.next = null;  
    } else {  
        tail.next = newNode;   
        newNode.previous = tail;  
        tail = newNode;  
        tail.next = null;  
    }  
}  

public void delete(int position){
    if (head == null || n <= 0) 
        return; 
    Node current = head; 
    int i; 
    for (i = 1; current != null && i < position; i++) 
    { 
        current = current.next; 
    } 
    if (current == null) 
        return; 
    deleteNode(head, current); 
}

//delete function
public Node deleteNode(Node head, Node del){
    if (head == null || del == null){
        return null; 
    }
    if (head == del){
        head = del.next;
        del.next.previous = null;
    }
    if (del.next != null){
        del.next.previous = del.previous; 
    }
    if (del.previous != null){
        del.previous.next = del.next; 
    }
    del = null; 
    return head; 
}

}