Unsubscribe followers from all projects and tasks or from the project(s)
Configure tool
Disable subscriptions
1b. Set the status of the contact is "Archived"
1c. On the tab "Subscription Management" select "Unsubscribe type", if "Unsubscribe type" is set with "Unsubscribe from the project(s)" select project(s)
1d. Press "Confirm action"
Suitable for enterprise and community versions odoo