how to hide print button when pdf is opened in browser using asp.net c#?

Question

protected void lnkView_Click(object sender, EventArgs e)
{
    LinkButton lbkFile = (LinkButton)sender;
    string FilePath = Server.MapPath("~/Uploads/Improvementdata/" + lbkFile.CommandArgument);
    WebClient User = new WebClient();
    Byte[] FileBuffer = User.DownloadData(FilePath);
    if (FileBuffer != null)
    {
        string extn = Path.GetExtension(lbkFile.CommandArgument);
        if (extn == ".jpg" || extn == ".png" || extn == ".JPG" || extn == ".jpg")
        {
            Response.ContentType = "image/jpeg";
            Response.AddHeader("content-length", FileBuffer.Length.ToString());
            Response.BinaryWrite(FileBuffer);
        }
        else
        {
            Response.ContentType = "application/pdf";
            Response.AddHeader("content-length", FileBuffer.Length.ToString());
            Response.BinaryWrite(FileBuffer);
        }    
    }