Hello,
What version of MS Word are you using? We have tested the "Remove Watermark" option available in MS Word with the included samples in the package and the watermark is removed correctly when the scope is the default value (header).
Please note that phpdocx allows adding watermaks in the following scopes:
Header (default) or footer.
Using the footer scope doesn't allow removing watermarks using the "Remove Watermark" option available in MS Word. In this case (footer scope), to remove the watermark, you need to select the header or footer and remove the watermark by selecting it. This doesn't happen if you use the header scope. To use the header scope, please do not set the scope option.
We have tested it with MS Word 2010, MS Word 2013, MS Word 2019 and MS Word 2021 and the behaviour is the same.
Please check the included samples and try again setting header as scope if you are using custom footer scope.
Also note that using MS Word, you many need to remove section watermarks one by one:
https://www.quora.com/How-do-you-remove-a-watermark-in-Word-from-all-pages-at-once
Please note that this is a MS Word requirement/limitation that we can't change. The same happens if the DOCX is created with phpdocx or any DOCX editor.
You can also use the watermarkRemove method to remove watermarks using phpdocx.
Regards.