How to rewrite url to remove default.aspx from my url

I really believe that the default.aspx is the default landing page in your application, if so, IIS would not bother asking for it even if you go to the URL without having the default.aspx concatenated to the URL at the end. So, you can try using the page without it.

You can use Visual C# for this,

// get the URL
var url = Request.Url;
// get the page user's at
// General URL: "http://www.example.com/default.aspx"
// Get the string at the index 4 (3 if talking zero based)
var page = url.Split('/')[3];
// If the page is default.aspx
if(page == "default.aspx") {
   // Redirect him
   Response.Redirect("~/");
}

You can edit your web.config file and write this code in it, to prevent the default.aspx in your URL. Reference.

<rewrite>
    <rules>
        <rule name="san aspx">
          <!--Removes the .aspx extension for all pages.-->
          <match url="(.*)" />
          <conditions logicalgrouping="MatchAll">
            <add input="{REQUEST_FILENAME}" matchtype="IsFile" negate="true" />
            <add input="{REQUEST_FILENAME}" matchtype="IsDirectory" negate="true" />
          </conditions>
          <action type="Rewrite" url="{R:1}.aspx" />
        </rule>
    </rules>
</rewrite>

.. and trust me, there are many (and many) other methods that you can use to perform such tasks. Url Routing is one of them.