How to make a admin on Factorio server
Adding Admin via console.
Log in to the Kinetic Panel.
Start the server.

Open console.
In console put
/promote usernameReplace username with the username of the player.

Enter the command & the user will be an admin.
Adding Admin via Files
Log in to the Kinetic Panel
Navgaite to file manager.

Open server-adminlist.json
Enter the user's name surrounded by quotes.

Save the file.

Restart the server.