I know that I can change the folder in which lightroom cc will save the originals by "preferences". However, I have a folder in my "windows" drive under --> "Users" --> "AppData" --> "Local" --> "Adobe". In this folder there is more saved than just the originals. I do not want this folder on my windows drive and would like to move it to my external harddrive.
Is it possible to run lightroom CC soley from an external harddrive
The AppData includes previews as well as originals. You can't simply move this file to a different drive. Lightroom needs access to it. You can change the location in the preferences, but from what I have read only NAS servers are allowed. Here's the information https://helpx.adobe.com/lightroom-cc/using/preferences.html.
You don't need to store originals locally though. Everything is already safely in the cloud. You could also reduce the size of the photo cache, so that fewer previews are saved in the AppData.