Is it safe to remove third-party antivirus software on Mac running Microsoft Word?

Not sure what Ms Word has to do with your Antivirus.

Macs don't really need AntiVirus apps and they tend to slow down the computer and cause issues.

The Mac has its own defenses, and having Word installed has no bearing on this.

Uninstall the AntiVirus app.

I'd usually explicitly disable Office macros, as those tend to be the biggest source of "fun" with Office documents.

Enable those macros only as and when and if you need them, and be skeptical about macros in documents from untrusted sources.

As for security, a Mac running macOS has built-in anti-malware including a built-in malware scanner and removal tool, as well as the signed system volume, gatekeeper and notarization, the app store, and other related mechanisms.

While not completely immune to malware (nothing useful is), installing malware usually requires the user to perform explicit overrides. Coupon apps and cracked apps and adware tend to be the common annoyances.

And some of the better known add-on anti-malware has been caught (and fined for) selling personally-identified browser history and web-purchasing history data.