(To affect the Population settings, select a computer on the lot, then MC Command Center.) Per MC Command Center, one of the ways you can prevent lots from being populated is to lower the 'Beds' count of each lot to 0, or to disable the Population_AllowHomelessMoveIn feature.
(Note: The link will take you off this site to the MC Command Center main site.) I have taken the initiative to get the information on this question from the FAQ: Thankfully I am a user of MC Command Center normally for MC Command Center, if you have questions, you can check Deaderpool's FAQ document on the mod.
