Install then run by clicking Extensions -> Document -> Delete Small Paths. With this very simple extension, you are prompted for the minimum width and height of the bounding boxes, and all objects selected that are smaller than either dimension will be deleted. Works best with paths. You may need to ungroup and or Path -> Break Apart and reselect all before running the extension.
To install, copy the files into the directory listed at Edit ‣ Preferences ‣ System: User extensions. After a restart of Inkscape, the new extension will be available. On Windows, this path is usually
C:\Users\%UserName%\AppData\Roaming\inkscape\extensions