Erase the edge and that hidden plane should go away.

No. The measurements box is intended only to accept typed values. It isn't a clickable box, either. That is, if you activate a tool for which a numeric value can be entered, you simply type the value. It sounds to me as if you might be better off to use an extension at can read your table. Look at the various extensions for point clouds.

The plugin I posted above was actually developed for that minichallenge (driven pushed me into it!), but never published.