Q: Is it possible to disable device's desktop and/or applications bar?

A: Yes, it's possible. In order to change this system behaviour the administrator must modify the file /usr/bin/matchbox-session as follows.
To disable the bar, comment (adding as the first character of the line the character #) the following command

matchbox-panel -nm --orientation south &

To disable the desktop, comment (adding as the first character of the line the character #) the following command

matchbox-desktop &