how do I make the rotation.z always = 0?

well Im starting a new game and I cant understand how am I making my player rotation.z=0.
here is the code:

Code (CSharp):

1. using System.Collections;
2. using System.Collections.Generic;
3. using UnityEngine;
4.  
5. public class Player : MonoBehaviour
6. {
7.     public float sensetivity = 5;
8.     // Start is called before the first frame update
9.     void Start()
10.     {
11.        
12.     }
13.  
14.     // Update is called once per frame
15.     void Update()
16.     {
17.         float mouseY =( Input.GetAxis("Mouse Y") *-1 *sensetivity);
18.         float mouseX = (Input.GetAxis("Mouse X")* sensetivity);
19.         transform.Rotate(mouseY,mouseX, 0, 0);
20.     }
21. }

 

Code (CSharp):

1. Vector3 playerRotation = transform.rotation.eulerAngles;
2. playerRotation.z = 0;
3. transform.rotation = Quaternion.Euler(playerRotation);

If you want local rotation instead, replace "transform.rotation" with "transform.localRotation"