Installing the secure your wordpress website Scan plugin will check most of this for you, and alert you to anything that you might have missed. Additionally, it will tell you that a user named"admin" exists. That is the administrative user name. If you wish you can follow a link and find instructions for changing that title. Personally, I believe that there is a strong password enough protection that is good, and there have been no successful attacks on the numerous sites that I run, because I followed these steps.
Also, don't make the mistake of believing that your web host will have your back as far as WordPress copies go. Not always. It's been my experience that the company may or may not be doing backups while they say that they do. Take that kind of chance?
Before you can delete the default admin account, you must create a user. To do this go to your WordPress Dashboard and click on User -> Create New User. Then enter all the information you need to enter.
Along with adding a secret key to your wp-config.php file, also consider altering your user password into something that is strong and unique. WordPress will tell you the strength of your password, but a good idea is to avoid phrases, use upper and lowercase letters, and include amounts. It's also a good idea to change your password frequently - say once every six months.
There are always going to be risks being online (or even just being alive!) And it's easy to get caught up in the panic. When we get caught i loved this up in the fear, we put the breaks on. This isn't a good reaction. Simply take some common sense precautions forge ahead. If something bad does happen, read the full info here it will need to be dealt with then and no amount of quaking in your will have helped. If nothing does, all is good and you have not made yourself ill.