How can I prevent my voice chat audio from being captured?

You can mute yourself. You can also turn your voice chat off:

1. Launch Fortnite.
2. Start a game.
3. Select the hamburger menu in the upper right corner.
4. Select the gear icon for Settings.
5. Select the speaker icon for Audio.
6. Select Voice Chat.
7. Set to Nobody.

You can also select Off When Possible from your voice reporting settings, but voice reporting will only be off in parties formed among friends where all players have voice reporting set to Off When Possible.

1. Launch Fortnite.
2. Start a game.
3. Select the hamburger menu in the upper right corner.
4. Select the gear icon for Settings.
5. Select the speaker icon for Audio.
6. Select Voice Reporting.
7. Set to Off When Possible.

Even if you turn Voice Recording Off there are some cases where it will remain On. For more info, check out: Why do I see Voice Reporting On in the sidebar when I turned it Off in the settings?

If you are Under 18 your guardian can edit the settings in Parental Controls. For more info, check out: How do I customize my voice reporting settings?