How to close the automatically opened annotation windows in Adobe Acrobat DC?

When I was reading a scanned PDF file in Adobe Acrobat DC, so many blank annotation windows opened automatically (my other PDF files are still clean).

It seems that every comment mark (include underline, comment, highlight ...) has a opened annotation in the right of Acrobat window like below:

Would someone please tell me why it happened and how to close these small windows? Thank you very much!