Remember this is a last minute fix for your document to give you a "clean" Word doc without any embedded EN field codes. Once you convert to Plain Text your document is no longer connected to the EN library.
If you need to add more citations or make changes to your citations in your original document - these changes will not be effected in the plain Word doc you have now created so you will need to edit the original document with EN citations and then repeat this process of converting to Plain Text.
EndNote in-text citations use coded or hidden fields - they usually display in grey when you click on them.
You can remove these coded or hidden fields from your citations to produce a plain Word document:
On a PC you can find this function under Convert Citations and Bibliography - Convert to Plain Text
On a Mac Convert to Plain Text can be found under Tools in the Menu.
EndNote will prompt you to save a copy of the original document with the EndNote codes embedded in it.