Deleting non-factory-installed apps from Apple Watch
Is there a quick way to delete all but the factory-installed built-in apps from an Apple Watch Series 2 (second-generation)?
Question marked as
According to these instructions
Delete apps from your Apple Watch - Apple Support
only the non-Apple apps even offer you the "x" to be deleted. So you can probably delete all of them within 60 seconds or so following the instructions in the link above.