If you use other software to convert PDF to WORD format, it means that PDF is not encrypted. It is recommended to use SolidDocument's SolidConvertPDF software. The WORD file converted by this software should basically keep the original style of the source file. There will be no watermark.
In addition, the problem that the watermark cannot be removed may be caused by the limitation of the converted file. Usually, the watermark may be in the background image or in the header and footer, or you can find and delete it.