|"I want to renew my registry completely"|
The only way to do that is to format the drive & do a clean install of XP.
How about stating the problem or problems you're having that prompted this repair installation?
You cannot delete the registry but you can clean it & there are a number of free programs available for that. CCleaner Slim (without the Yahoo Toolbar spyware) & Glary Utilities are two that will clean the registry along with all the accumulated garbage files.