Rather than removing things, you are better off starting with the IoT version of the Debian Release.
It is about half the size of the LXQT version, and all it does is remove the GUI and drivers.
If you want to build a smaller custom application version, you can start with the “console” version, which is about one fourth the size of the LXQT version, but you will need to add anything you need for the application.
Yes, ideally I'd just install a console image but I can't.
This all stems from my Debian 7 BBB that refused to install a newer
image despite all my efforts.
I've finally managed to get it to upgrade itself by changing all the
references to 'wheezy' to 'jessie' in /etc/apt. However this means I
still have a full GUI install.
I *can't* (for whatever reason) install a new image so I want to pare
down the current installation somewhat to save some space. It's not
particularly tight at the moment but it would be nice to have some
more spare space and updating all the GUI stuff that I will never use
seems pretty silly as well.