@eSwami
That would be hard to do since the radio button is a form input field.
You can
add a better description to the language file as an easy fix to assist your clients.
Open your
components\\com_dtregister\\languages\\english.dtregister.php file in notepad, search for (ctrl+F) and edit the line containing;
define(\"SELECT_OPTION\",\"SELECT REGISTRATION TYPE\") ;
Change it to something like;
define(\"SELECT_OPTION\",\"Please click EITHER BUTTON below to select your REGISTRATION type, groups or individuals\");
Once you have edited this, click file, save and upload it to your site.
This will at least define what to do on that page.
Good luck!