Canceling fortnite crew - what's the trick?

the stuff you already got from crew stays yours. skins and v-bucks from the months you paid for don't vanish when it runs out, you just stop getting the new month's things.

You cancel it wherever you bought it. Paid on PC through Epic, it's in your Epic account settings under subscriptions. Paid through PlayStation or Xbox, you have to cancel from that console's subscription page, Epic can't touch it. You keep crew until the end of the month you already paid for.