When you have installed your server, you need to log in. GitLab comes with a built-in administrator account.
Log in using the username
You need to choose a new password; pick whatever you like.
Log in with the new information.
Go to the Admin area section, as shown in the following screenshot:
Navigate to Users | New User.
Fill in the information to create your own user. Don't forget to check the Admin checkbox.
Now, click on Create user.
An e-mail will be sent to the given e-mail address. This e-mail will contain the new password for this account.
Go to the Admin area section and click on Users.
Click on Block for the administrator account.
As GitLab ships with a default administrator account, this makes it a bit unsecure by default. Therefore, when you don't change anything about your setup, everyone will be able to log in.
To ensure that we have a secure GitLab installation, we created a new administrator account, and gave it an administrator access. We also want to be sure that the default shipped account is not useable anymore, so that's why we logged in with our own account and disabled the account given by GitLab.
We had to log out first, as GitLab does not allow us to disable the account that is currently logged in.