well you have come to the right place
7 Admins that crazy, logon your mail Admin account (the one you want to keep) and goto:
Contol Pannel > User Accounts
You can click on the username and delete them from there or if the Admins are not listed try:
Contol Pannel > Administrative Tools > Computer Management
Find the folder on the left-hand side named:
Local users and groups
when you click that click on the folder named Users and to delete a user right-click them are select delete.