You can use EmptyDataTemplate in gridview to show No Available Records
As for example you want clear the records from gridview
In HTML Side
<asp:gridview id="GridView1" runat="server" xmlns:asp="#unknown">
<columns>
<%-- Put your column names--%>
</columns>
<emptydatatemplate>
No Available Records
</emptydatatemplate>
</asp:gridview>
In code behind At clear button
GridView1.DataSource = null;
GridView1.DataBind();