DirectAdmin determines the admin password during installation and saves these passwords into the file called setup.txt.
You can find the admin password from the file
/usr/local/directadmin/scripts/setup.txt------
adminname=admin
adminpass=xxxxxxx
------
where adminpass=xxxxxxx is the admin password generated during DA installation.
To change admin password, login the server as root and execute:
passwd adminEnter your new password here.
That's it