Locate the adminlist.txt
The main file where all admins will need to be placed is the adminlist.txt
This can be located in your File Manager in the /save-data/Settings/ directory or folder.
Add Your SteamID64
Once you’ve found your admin configuration file click to Edit the file. This file by default will be empty. To add your Steam account as an admin for the server you’ll need to enter your SteamID64 on an empty line.
For multiple accounts each SteamID64 will need to be on its own line.
To find your SteamID64, the easiest way is to go to your Steam profile, copy the link to your profile, and paste it into the following online tool. Please note that other tools and methods exist. We do not endorse any particular tool and are not responsible for the tools used for this purpose.
Once this file is saved you have successfully added yourself as an admin!
You must restart the server.
Using Admin Commands
To enter commands for your server your game console will need to be enabled and you will need to be connected to the server.
Once you have joined your server open your Options. Under General make sure Console has been Enabled.

Once that is done go back to the game and press ~ to open your game console.
Enter adminauth to get access to all Admin commands.
You should see the You now have Administrator priveleges (SuperAdmin)! in your chat to confirm the commands success.