Starve them by turning them all into taxmen. Recruit them all into the IRS and you'll boost your treasury. If you are runninig 10%/40 turn research make one of them a scientist to keep that going and drop your science budget to zero.
When you get down to one citizen then build them back up again as fast as possible.
The only problem you will have is that during each turn one will starve, they will then rearrange themselves to work the food tiles, and you have to go round and set them back to taxmen again. But it's worth it as you finish up in a few turns with cities you can call your own, less war weariness, and no rep hit from razing them.