prefixOptions.separator Boolean (default: true)

If set to false, the prefix adornment will not have a separator.

Example - specify prefix adornment separator

<input id="prefix" />
<script>
  $("#prefix").kendoMultiColumnComboBox({
    label: "MultiColumnComboBox",
    dataTextField: "text",
    dataValueField: "value",
    dataSource: {
        data:  [
            { text: "Apples", value: "1" },
            { text: "Oranges", value: "2" }
        ]
    },
    columns: [
        { field: "text", title: "Text" },
        { field: "value", title: "Value" }
    ],
    prefixOptions: {
      template: () => `${kendo.ui.icon("search")}`,
      separator: false
    }
  })
</script>