For now, just like the BSD Subsystem, you can only reinstall Cydia Packager, not uninstall. About the Fake BSD, I agree that it requires better explanation, and here it is:

Quite a few applications on Installer require the BSD Subsystem, Cydia Packager provides better versions of exactly the same files as BSD Subsystem, now if you start out fresh, and install Cydia without having BSD, Installer.app repos don't know that you have these files because BSD isn't installed, but you DO have these files because they came with Cydia. So in this situation, you would install Fake BSD in order to trick installer into thinking you have BSD, and allow applications that require it to install properly.

Note: If you have previously installed BSD Subsystem, you do NOT need Fake BSD, because Installer.app still thinks BSD is installed, and you're fine.

Also, do not reinstall or update BSD Subsystem after installing Cydia, as this will break Cydia, you will never need BSD again after installing it, so don't worry about it

I'd also like to point out that Cydia comes with a working 'passwd' utility, so you can now safely change your SSH password without breaking your phone!