Sync doesn't do anything or affect Firefox use in any manner, until you activate it.

You can try removing files from Firefox to "remove Sync" from your installation, but you would probably break the installation. Sync is built-in, not added on.

Thanks for that, but Firefox for Android sticks a very large banner across the start-up screen of my tablet. It's an irritant, which I suppose was the objective of the developer, but I really want rid of it. Surely the design isn't so sloppy that there's no switch/flag to permanently prevent the nag??

You can try to set some sync String prefs that link to Mozilla sites to an empty string on the about:config page and possibly check for Boolean prefs as well.

Be careful and make a note of prefs that you've changed, so you do not forget about them in the future.