Keep An Image For Vista?

before this i try to install vista on my machine. and for sure in that time we need to create user (adminstrator) before we start using the vista. after that, i try to keep an image for my vista because if anything happen, it will be more easier to me. then, i try to image on my machine again. but, there already have i user which mean the administrator that i create during the 1st installation. so, when i do the image, i need to put the different user name because the user name that i try to create already exist. so that will create 2 different user when imaging is done. is there any way how to delete the 1st user? so when imaging is done, it will only 1 user (new user) and the windows will be automatically show the desktop. (i know how to delete from control panel>user account). actually this is for my client.