1.) It would be easier to just change the email address and contact information (if needed) of the original user that you created. Otherwise you will have to give the new user you created admin rights, then log in with that new user, then remove admin rights from the original user.
2.) In order to delete a project you need to have the proper permissions. If a project is grayed out, that means that you do not have access to edit or delete that project. If you make sure that your new user has admin and super user rights, that account will always be able to delete or modify any project in the account. Otherwise, you have to be either the project manager or manager of the project to be able to delete the whole project.