My take a third option suggestion : remember that story about the guy who traveled across the border every day with saddlebags full of hay? And it turns out he was smuggling donkeys? (Or a kid with bikes, or a guy with a wheelbarrow of rubbish...)

Take the city 'away' one bit at a time. Ask the emigrants to smuggle bricks out in their bags.

It'll take longer, but it'll be less noticable, make the bad cost seamless worth it, and you wont have people in favor of the system calling you "violent, destructive [slur]s."*

*Seriously, I've been trying to soften some aquaintences' attitudes towards recent social movements, and the biggest/most effective counterargument is "I'm not supporting vandals/arsonists!"