Hi 895077 ,
Check there would be one publishing database . In that database search for das_account table. it would be there.. delete all the rows in that table .
Now check your application server . there would be one atgPublishing server instance . run this instance. and check...
On server startup, ATG automatically creates a set of standard user accounts, groups, and privileges if they do not already exist by default. Only exception to this is when liveconfig is enabled. In a typical setup all this default account and access information goes to das_account table. Check if you can see the /atg/dynamo/security/AdminAccountManager component running the account initializer which would populate the das_account table. If it is not running then you may check whether you have liveconfig enabled.
For more details refer this http://docs.oracle.com/cd/E24152_01/Platform.10-1/ATGPlatformProgGuide/html/s1404configuringthedefaultloginaccoun01.html