I doubt removing stuff would deter thieves. In most surveillance videos I've watched the thieves are stealing bikes to resell or strip for parts. They'll just walk the bike away if the pedals or saddle are missing. If they're brazen enough to steal a bike in the city surrounded by passing pedestrians and cars, they won't be deterred by the lack of pedals if they spot a bike with usable parts.

I've seen one or two surveillance videos of bike thieves in which the thugs went to a lot of trouble to steal a bike, then rode it around for a few minutes and dumped it on the street or sidewalk. These looked more like dare thefts, just a bunch of thugs stealing and vandalizing stuff for the same reason cats and dogs mark their territory by pissing on everything.

I remove and lock the saddle on my bike because it has a silly and superfluous quick release clamp. It might deter a thief for a few moments. But if I'm worried enough I'll lock the bike where I can see it from the restaurant or store.