Anyway to hide touch screen keyboard when onSelect input field?

I’m implementing my own vr keyboard, but when I invoke onSelect inputfield, touch screen keyboard pops up and covers half of the screen. I don’t want the touch screen keyboard to pop up.
Here are several things I tried.

  1. Toggle on Hide soft keyboard on the control settings.
  2. Make a new class inheriting from TMP_Inputfield and set the keyboardType to -1. Below is the written code.
using System.Collections;
using System.Collections.Generic;
using TMPro;
using UnityEngine;

public class TMP_InputFieldWithoutTouchScreenKeyboard : TMP_InputField
    protected override void Start()
        keyboardType = (TouchScreenKeyboardType)(-1);

But still the keyboard shows up. Could there be any other way to stop touch screen keyboard from appearing? Or at least close the touch screen keyboard as soon as it emerges.
I would really appreciate it.
Thank you in advance.