1. A concise explanation of the problem you’re experiencing.
2. A minimal code example. If you’ve found a bug, this helps us reproduce and repair it.
3. Context. Why do you need to do this? We might know a better way to accomplish your goal.
4. The Cesium version you’re using, your operating system and browser.
Please stop spamming the forum with so many posts. A single new post is more than enough to get the community’s attention.
To answer your question. Cesium’s official tool for creating terrain is via Cesium ion (https://cesium.com/ion) You can create a free account and upload .DEM and other terrain files which will be hosted back to you for use in your Cesium applications. For a quick getting started tutorial, see https://cesium.com/docs/tutorials/getting-started/