I explains here how we can use sortition to designate an impermanent moderator.

Before casting the dices decide together on a maximal time to be a moderator: it could be 10 minutes, an hour or even a day. Then cast two different coloured dices, it gives 36 distinct throws, each equiprobable. 1/1 the thrower becomes the moderator, 1/3 the second person on the left becomes moderator, 5/1 the 6×5 – 1 = 24th person on the thrower’s left becomes the moderator. You can also throw a single dice. The former moderator is next to cast the dices so power turns.

You don’t have a dice? You can use a coin, in this case: heads the first person on thrower’s left becomes moderator; tails it’s the second.

A sortition method summarized in a figure. Romain Cazé CC-BY.

This method most simply describe how sortition can work.