In my opinion PD does not save precut files, whenever you open the project you will need to load the original file.

Shadow files are saved and will be automatically deleted after 30 days is the default.

If you produced the pre-cut video and didn't select a folder, check the location in Settings, Preferences, File, Export Folder

PD doesn't save any actual precuts, but it does lock the precut settings to each clip so they will always appear whenever you use that clip in a project. If you only needed the precuts for a single project, you can simply ignore the Media Library subfolder or edit/delete the precuts. See this discussion and this one for more info.

Another way to get rid of the precuts is simply to rename the original clip outside of PD before importing it. Adding a number or space will force PD to ignore all precuts that were originally applied.

Quote PD doesn't save any actual precuts, but it does lock the precut settings to each clip so they will always appear whenever you use that clip in a project. If you only needed the precuts for a single project, you can simply ignore the Media Library subfolder or edit/delete the precuts. See this discussion and this one for more info.

Another way to get rid of the precuts is simply to rename the original clip outside of PD before importing it. Adding a number or space will force PD to ignore all precuts that were originally applied.

Thanks.. This helps me a little bit

I've find a new way too.

If u delete 'scene.db' in roaming folder of cyberlink then it will also delete precut settings.

Btw
Is it fine to delete scene.db? My gut feeling says 'scene.db'is an important file. Anyone knows?

It sure look like you found the right file and nobody else has ever posted about that particular clip.

It looks to be a SQL database and the safest thing to do would be to keep it in the recycle bin (in case you need to restore it) or simply rename it with PD closed to get rid of the precut data.

BTW you have also solved a related issue with regard to the MotionTracker tool, because ClipMarker.db, MotionTracker.db and Scene.db are all located in the same folder, which is C:\Users\{user name}\AppData\Roaming\CyberLink\PowerDirector\{version #}.0\UserConfigure\CacheDBFiles.

Deleting/renaming the appropriate database file will permanently clear all the stored motion tracking and clip markers. This is a great discovery!

I closed closed PowerDirector (latest version 20), found the motion tracker database file, deleted it, opened Power Director, reloaded the project... motion tracker is still there on the affected clip.
Removed the clip from the timeline, reimported it - motion tracker still there.
But this was just one clip of 3 from the same source file, so next I removed all clips that were sourced from the same file, saved the project again, closed PowerDirector, checked to make sure the MotionTracker.db file hadn't been resurrected (it hadn't), opened PowerDirector, reimported the clip - and the motion tracker is still there.
So, clearly this motion tracker is hiding somewhere.
Now I have an older version of the project file from before when I added the motion tracker, so I load that project. Now the motion tracker is not visible on the afftected clip.

*** UPDATE ***
I've found the other post about motion trackers mentioned above by Optodata. The fix is laughably simple - but not intuitive! The motion tracker tool actually adds new video overlay tracks onto the timeline, but you need to scroll down in the timeline window below the affected clip to see them. Then you can easily delete them