You can also remove themes without removing the BURG Bootloader.
Just open a terminal (Alt+F2) And Type:
And navigate to the Root Drive.
Navigate to boot/burg/themes.
And Move all of the theme folders to the trash you wish delete.
However, Do Not Delete All of the Themes in the boot/burg/theme folder.
Leave one theme in the boot/burg/themes folder.
Or you can Delete all the theme folders in the /boot/burg/themes Folder,
And Download at least one theme and extract the zip file. Then, Open a terminal and type
and navigate to the folder where you extracted the theme folder.
Move it to the /boot/burg/themes folder.
And finally, run this in a terminal: