Is the ability to automatically unmatch everyone in your database from FamilySearch an active feature request? If not, it should be. This feature for Ancestry trees is very useful.
I wonder if the FamilySearch Central option shown as “Reset” (below “View”) in “What’s New” would accomplish that? Do a Backup and give it a Go…
That “Reset” button is to clear the “What’s New” list. There isn’t an option to remove the FSID from everyone. The request has been reported to development.
potential to do via Sqlite (SQL) if that is something you want to explore. Make sure you have 2 at least recent backups