Assuming you have saved the scores locally to your computer, they are found at C:\Users(username)\Documents\MuseScore4\Scores and you can simply delete the files there. Understand that is permanent, not simply removing from the list. If you want to archive them, then move them to a different folder, external drive, etc. That will also remove them from the list. Someone else may chime in with an alternative, but that is the only way I know.
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Assuming you have saved the scores locally to your computer, they are found at C:\Users(username)\Documents\MuseScore4\Scores and you can simply delete the files there. Understand that is permanent, not simply removing from the list. If you want to archive them, then move them to a different folder, external drive, etc. That will also remove them from the list. Someone else may chime in with an alternative, but that is the only way I know.