I have a drop down where the user selects a language:
<option value="" selected disabled hidden>Default Text</option>
Leaving the disabled flag in prevents them from not selecting an option and the hidden flag will remove it from the list. In my case I was using it with an enum list as well and the concept holds the same
<select asp-for="Property" asp-items="Html.GetEnumSelectList<PropertyEnum>()">
<option value="" selected disabled hidden>Select Property Enum</option>
<option value=""></option>
</select>