stopping an ui element from moving if the y axis value is too low

here's the script:

 using System.Collections;
 using System.Collections.Generic;
 using UnityEngine;
 using UnityEngine.SceneManagement;
 public class Options : MonoBehaviour
 {
  
      RectTransform canvas;
      RectTransform button;
      Vector3 startingPosition;
      public float speed;
      public static bool yees;
      public GameObject canvaes;
      void Start()
      {
          button = gameObject.GetComponent<RectTransform>();
          canvas = GameObject.Find("Canvas").GetComponent<RectTransform>();
          startingPosition = transform.position;
          
          speed = -5f;
          
      }   
 public void OnPressed()
  {
 yees = true;
  }
 
 
 void Update () 
 {
    if(yees)
 canvaes.transform.Translate(0f, speed, 0f);
 
 }}  

basically what it does is it makes an ui element move endlessly downwards if the OnPressed function is activated. what i want it to do is to stop at a certain point on the y axis. i'm kind of confused as to how the RectTransform works, so i would be thankful if someone could tell me w$$anonymous$$ch value i should check for to acomplish t$$anonymous$$s goal.