Mark the team as Won't continue next round in the round's standings. The team finishes its current round as normal, and it is left out when you import teams into the next round.
How to mark a team
Go to Play → Leagues and open the round.
Open the Standings tab.
Click the ... menu on the team's row.
Choose Won't continue next round.
No confirmation is needed.
What happens next
When you import teams into the next round, the preview lists the team under "Not continuing next round" and skips it.
Their place stays open. Fill it from the waiting queue or by dragging teams after the import.
Changed your mind?
Click the ... menu on the team again and choose Include in next round.