how to disable multiple options if one option is selected in the forms

Solution 1:

You can do this with javascript by hiding options in the second elements whenever the first select element changes by checking its value and hiding elements accordingly like so:

// Select Elements
const first = document.getElementById('first')
const second = document.getElementById('second')

// Option Elements
const one = document.getElementById('one')
const two = document.getElementById('two')

// Runs whenever first select has changed
first.onchange = () => {
  // Checks First Selects Value
  if (first.value === '1') {
    // If '1' then hide TWO and show ONE
    second.value = 'ONE'
    one.hidden = false
    two.hidden = true
  } else if (first.value === '2') {
    // Else, if '2' then hide ONE and show TWO
    second.value = 'TWO'
    one.hidden = true
    two.hidden = false
  }
}

<select id='first'>
  <option>1</option>
  <option>2</option>
</select>

<select id='second'>
  <option id='one'>ONE</option>
  <option id='two'>TWO</option>
</select>

This is a very basic example and can be improved alot.

Solution 2:

you can do something like below, so when you do selecting none, other options would be disabled, and other than none it would be enabled again

function disabledEnabled(event) {
  var optiosLists = document.getElementById("exam2").options;
    
        
        for (let i = 0; i < optiosLists.length; i++) {
             if(event.target.value === "None"){                 
                 optiosLists[i].disabled = true;        
                  optiosLists[0].disabled = false;
                } else {
                    optiosLists[i].disabled = false;    
                }
            
            
    }
    
}