How to enable disable HTML Anchor Tag in ASP.Net

You cannot since that anchor tag is not a server control. Add runat server and then disable it

<asp:panel ID="panel1" runat="server">
 
<a id = "lnk" runat = "server"  href="~/Default.aspx">HOME</a>
 
</panel>

Now in code

lnk.Disabled = true;