The Zotero MS Word plugin generates code, that is hidden in your Word document, and enables Zotero to communicate with Word. This code increases the file size and many publishers request that you remove this code when you submit your paper for publication. You should also remove the code when submitting a paper to Turnitin, UCL's plagiarism detection software.
You should only remove the code when you are sure you have finished editing your document.
As well as a requirement for submission, this also allows you to make small manual edits to your references in Word if required, useful if your output style means a reference isn't displaying as needed. This process is not reversible so make sure you save a copy of your original document with the fields code, in case you need to go back and make further edits.
Keep a copy of your original document with the field codes in case you need to go back and make further edits.
To remove the Zotero field codes from your Word document:
Click on the Unlick citations button on the Zotero tab.