You can safely delete any unwanted HTML elements but never delete any server-side ASP.NET elements (elements that begin with "asp:" prefix) as these server controls are needed by the application to run. 

For example, you can delete the <a href="/somewhere" /> because this is just a plain regular HTML element, however, you should not delete <asp:HyperLink runat="server" NavigateUrl="/somewhere" />.

Instead, you should use CSS to hide the unwanted ASP.NET elements. For example, you can add the style="display:none" or style="visibility:hidden" to the ASP.NET element.