Fantasy Trip Wizard dismissing spell?

[DHood64]

Sorry for question likely already asked - but I dont see a way to search "dismiss spell" - it seems to find "spell" - which is too common a word.

Using the latest rules, if a wizard casts say 3 hex fire, but before it would naturally expire, they want to dismiss/cancel the spell. Can the wizard dismiss it early in some way? What are the mechanics to dismiss (takes action as if casting a spell, or free action? only on wizard's turn? all 3 hexes cancel as one action? etc).

If this is in the book, can you please share what page?

Thanks.