Choose the data you intend to remove
A title’s current watched flag and the log of past viewing events are different records. Plex says deleting Watch History removes that activity and resets profile watch counts, but does not change watched state. If the aim is to make a film appear unwatched, clearing history is therefore the wrong assumption to make about the outcome.
Read the separate synced-data control
Plex documents another action for deleting synced Watch State and Ratings, with sync disabled first. That action does not delete watched state or ratings stored on personal servers, and does not delete Watch History. Opting out of future sync also leaves previously synced data in place. These distinctions matter before selecting a broad deletion merely to tidy one profile section.
Work through one explicit goal
For example, a viewer may want past activity absent from a social profile while retaining useful watched flags in a personal library. Inspect the history control and current privacy preferences rather than selecting every deletion option. Someone wanting a fresh watched-state library has a different task and should inspect the server’s actual records separately. Review confirmations carefully and keep a private note of the chosen scope. A completed deletion is not proof that future activity collection stopped; Plex says later activity can still be added according to the current source and sync settings. Check the profile activity and the library watched flag separately after the intended change.
Questions, answered
Does turning sync off delete earlier synced records?
Plex says opting out stops future personal-server sync events but leaves previously synced information.