Edit area on terrain

Hello. I've baked nav mesh area and it looks like this:


Now I'd like to make this area unwalkable:


I'd like to just edit the baked area. I would like the navmeshagent to walk only on the path. For example:


It's worth adding that ground is terrain, not normal mesh. Is it possible?

Regards

 

You'll have to cordon it off with Colliders. Make sure to visually communicate this with the players somehow, else they'll be confused why they can't reach those spots.