JSFiddle - React, Tailwind, and code Playground
HTML
<input type="text" value="red,yellow,blue" id="colors" />
<select name="colors_dropdown" id="colors_dropdown">
<option value="red">red</option>
<option value="yellow">yellow</option>
<option value="blue">blue</option>
</select>
JavaScript
var selected_colors = $('#colors').val().split(","); //array of colors from text input
jQuery.each(selected_colors, function() {
$("#colors_dropdown option:[value='" + this + "']").remove();
//Or use text attribute:
//$("#colors_dropdown option:[text='" + this + "']").remove();
});