I cannot make the red vertical lines on the left side disappear

This red line is there because there are still changes in the document that need to be accepted (which can be minor changes like double spaces or a wrongly placed comma).

Step 1: Go to the REVIEW tab and click on ‘Accept’ (Word 2013).

Step 2: Click on ‘Accept all changes’.

Accept all changes Word 2013
Accept all changes (Word 2013)
Accept all changes Word 2010
Accept all changes (Word 2010)
Accept all changes Word 2007
Accept all changes (Word 2007)
Accept all changes Word 2003
Accept all changes (Word 2003)