Deleting apps from Apple Watch 3
How do I delete unwanted apps off my Apple Watch that were automatically installed, like Stocks and Walkie Talkie?
Apple Watch Series 3, watchOS 6
You can delete the Stocks app but not the walkie Talkie.
To make it easier,
on your paired iPhone :
Watch app > My Watch > App View > change to List View
On Watch:
Click the Digital crown
Swipe left and tap the X on the app you want gone.
List of apps you can delete => Remove built-in Apple apps from the Home screen on your iOS 10 device or Apple Watch - Apple Support