Since I joined two or three season ago, I keep auto-joining new season without any warning.

Just got 6 booted games because I didn't pay attention (haven't logged in for a while) to the ongoing tournament.

Is there a way to leave the queue for newer tournaments?
Like, If I want to play it, I'll join it...

The Seasonal games are from the Seaonal ladder. Like all ladders, it will keep inviting you to games until you leave the ladder.

You can leave ladders from the ladder page, for seasonal that is https://www.warzone.com/Ladder?Ladder=Seasonal

Thanks, yes, looks obvious said like that.
But I expected to join for the ongoing season, not join every season. ^^

Thanks for the answer.