title: How to disable selection or grey out the for particular value in List of value items of drop down list (<ng-selectize> or <options> ) in anguarl 7
body: <p>I have scenario where i need to populate list of values for a dropdown list in angular 7 app. But i should grey out the particular value from that list based on condition or flag. </p>
  
  <p><strong>Eg: I am populating alphabets in UI with drop down list (a to z letters)-> among them i need to disable letter "N" when user try to select that .</strong></p>
  
  <p>Can any one suggest me how we can do in angular 7</p>