When I open files with libre office, it will look like this. How to close it or fix it?

Withot a sample file showing the issue for you, I can’t tell.

It looks like a pdf or maybe Word from some handwriting-to-text application. The handwriting is kept so that the author can check that the interpretation is the same as what he wrote. In this case it seems that md has been interested as mid or maybe the handwriting does say mid, hard to see.

At you are in Draw you could delete the handwriting layer if you wished.

I wonder what the pdf (assuming it is) would look like in Acrobat Reader or Word?

Open a handwriting document with Libre Office, will it auto-generate the same text box as the handwriting text?