Server side script for Hiding controls

 public void hidecontrl()
        {
            StringBuilder sb = new StringBuilder();
            sb.Append("<script type=\"text/javascript\">\n");
            sb.Append("Sys.Application.add_load(hidebtn);\n");
            sb.Append("function hidebtn() {\n");
            sb.Append("$('input:imagebutton[id$=imgbtnAnnouncEdit]').hide();\n");
            sb.Append("$('input:imagebutton[id$=imgbtnAnnouncDelete]').hide();}\n");
            sb.Append("</script>\n");
            Page.ClientScript.RegisterStartupScript(Page.GetType(), "Startup", sb.ToString());      
        }
      

call hidecontrl(); in whichever function you need.