To become admin on your Ark server you will need to use the admin password from Clanforge and input it via the in game console. 

1. Log into your server like normal through the in game browser or via steam server viewer:

2. Locate the "Admin Password via Clanforge>Edit Profile>Settings:

3. Open the Console in game by pressing TAB and input : EnableCheats <Password>

Your account will then have admin allocated to the server.

Further console commands can be found here :