The only way to recover some disk space on Siberian is via your Backoffice > Dashboard:

Here you can clear all, it has absolutely no impact on the functionning of Siberian CMS:

• “Log” is the folder which contains the error log files that are generated when there is an error in your system. You can clear that unless you have some errors and you want to use the logs to resolve them.
• “Cache” is the folder in which some files of your Siberian are stored to speed up your Siberian (the files are not regenerated, the stored files are used). If you have some weird displays in your Siberian (for example, white text color while you haven’t chosen white for text color), you can click on clear. Don’t clear the cache too much because it has to be regenerated each time it is clear and that would slow down your CMS.
• “Temp” is a folder in which are stored temporary files (files that you will use at a specific moment and that can be generated again), like the APKs that are generated, the zip file of the app source code. You can clear the folder to remove all the files and gain some disk space if needed.
• “Overview” is the cache of the “editor” and HTML5 versions of your app.