Unable to remove vegetation around Runway Heading

After so many tries following instructions step by step to remove trees, it shows that is working while editing displaying no trees but after closing all SDK windows included Scenery Editor the vegetation grows back, although. that the Save Scenery was previously saved.
I would appreciate any help

Hello @Ppli2

Does the rest of your scenery also disappear when you close your Scenery Editor ?

If yes, you should try to build your package before closing the Scenery Editor.
In order to have a functional package in the sim, it has to be mounted.
You can achieve this :

You can then check if your package is mounted via the Packages Tool.

Also, may I ask you what technique you have used to exclude vegetation from your scenery?

Hope this could help you,