Tournament Frequency

Good afternoon. I would like to know how i can create a tournament which is a one time event only.

When i create a tournament and leave the tournament frequency blank, ther is a notification that this bar cant be blank. So i have to choose between daily, weekly, monthly and Yearly.

Can you please give me a clue where to deactivate it? maybe in php itself, but i already searched in the forum and the line does not fit actual products i think
–> wp-content->themes->arcane->single-tournament.php

Thank you in advance
Jan