They're not subclips. They are clips that got broken up because there was a timecode break and you had the "Upon timecode break -- Make New Clip" User Preference selected.
If your tape has timecode breaks, not much you can do about those except to log around them. My guess is that while logging, you overlapped the clips (which is
usually a good practice, but not when you have timecode breaks every time the camera stops recording), so you're getting a tiny piece of the previous shot and the upcoming shot.
But deleting those clips is easy. Learn the SHIFT-D (Make Offline) function. It gives you options to leave the files on disk, move the files to Trash, or delete right away. This allows you to erase/Trash/permanently discard the files without going into Finder.
www.derekmok.com