In drupal 6 I have created an admin user with the permissions to add, edit and delte all kind of nodes. The problem is that I am unable to edit nodes through this newly created admin user which are created by user1. any idea ??
I think, you did not assign "edit any [contenttype] content" permission to newly created admin user, so this user does not have access to edit content created by other user.
You can follow below step for configurations.
Kindly see that [contenttype] is content type in your website. If you want to allow newly created admin user to edit all content created by other user, you need to give permission for all content type.