Every Teams deployment has some defunct or obsolete channels. In this article, we explore how to mark unwanted channels as defunct before their eventual removal. It’s a manual but very easy technique that’s very effective when explained to users. As long as everyone remembers to recover any required information from channel conversations before its deletion, everything goes swimmingly.
https://office365itpros.com/2021/10/15/how-to-mark-obsolete-teams-channel-defunct-before-removal/
