Hello,

Can you check if the button is there now?

The game admin panel opens when you press on your flag, and choose game admin.

Kicking inactives is not possible on all system generated maps (except the 22p map since it also can be user generated).

Update notes state it was removed from the system generated maps, as it was used more to wolf-pack than anything else. It's hard playing a 100p with only 20 people on day 7, but the other option is for the round hosts to get friends to join the map as soon as they kick the inactives, finally, on day 20.