If you don’t want to redo or edit the vanilla navmesh in the Skyrim SE Creation Kit, a simple workaround solution is to add a collision box and use that as a “navmesh cutter” instead. Here’s how. 
Creation Kit
CK Quick tip: Wildcard Replace
Wildcard Replace is a new feature of the Fallout 4 Creation Kit, that makes it easy to replace multiple references at once. Here’s how to use it.
CK Quick Tip: How to preview objects
Many of the objects in the Creation Kit’s object window, such as statics, items and actors, can be previewed in a separate preview window. Here’s a short text that explains how.
CK: How to remove fog from interiors in Fallout 4
Fog in interiors can be very atmospheric, but other times you just want it gone. Here’s a short Creation Kit quick tip tutorial on how to remove fog from interiors in Fallout 4.
How to do a simple material swap in the Fallout4 Creation Kit
Swapping the materials on many of the static pieces in the Fallout4 Creation Kit is easy, but a little hidden away unless you know where to look. Here’s how.
Day/Night emittance from windows (CK)
How to set up a day/night light emittance from interior windows with the CK for Fallout 4, so that the light that appears to be coming through the windows will change with the time of day.
How to change the viewing distance in the CK
When doing landscaping in the Creation Kit with the default settings, static objects and bordering cells will often tend to dissappear from view a little too often. Luckily, if your computer is up to it, the solution to the problem isn’t complicated…although a bit hidden:
Chiaro's 