Removing some built-in Apple Watch apps, like Cycle Tracking, must be done from the Watch itself. You can't do this from the iPhone's Watch app.
- On the Watch, open the App Grid by pressing the Digital Crown (if you're in the List view, press firmly to change to the Grid view first).
- Lightly tap and hold on any app to start the familiar 'wiggle' mode. If you press too firmly you'll trigger the List/Grid view.
- Icons with an 'X' on the top can be deleted. After tapping the 'X' you'll be asked to verify you want to delete the app. Select 'Delete'.
- Release the pressure and tap on this button to delete the app.
From the List view you also slide the app name to the left and select the red delete (trash can) button.
Apps like Mail, Maps, Music, and Photos are still permanently installed and you can't delete them.