Hello,
You can write a onsubmit script which will have the logic that if the chosen option is the one we just return false and the user is not able to submit the form.
The script will look something like below:-
function onSubmit(){
var mandatoryVar = g_form.getValue('fieldname');
if (mandatoryVar =="optionwewanttostopfor"){
alert("You cannot submit for this option");
return false; }
}
https://support.servicenow.com/kb?id=kb_article_view&sysparm_article=KB0622896
Please mark my answer as correct based on Impact.
