You can prevent a watermark from printing by clearing the option to "Print drawings created in Word" at File | Options | Display.

However, since that option is user-specific and machine-specific, it won't apply when you send the file to someone else, unless the recipient also clears that same option.

As an alternative, you can convert the document to a PDF before sending it to your colleague.

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Stefan Blom
Microsoft Word MVP

Microsoft 365 apps for business
Windows 11 Professional