How do I remove the Nike running app from my Apple Watch 3 Nike + screen?

In addition to the exclusive Nike-branded watch faces, Apple Watch Nike+ also includes all of the standard watch faces offered under watchOS for your model:

Faces and features

These can be added to the collection on your Apple Watch and customised with the complications of your choice (including none at all, if preferred):

• Customize your watch face
• Change your watch face - Apple Support

Hi

Follow the instructions here to uninstall an app:

Use apps on your Apple Watch - Apple Support

Keep in mind that complications for the Nike+ Run Club app are a permanent feature of the exclusive Nike watch faces on Apple Watch Nike+ models.

Did you try this? I’ve ordered the watch and want to use RunKeeper or Strava and want to make it an ordinary Iwatch.