This has been a common issue, and the basic answer is that there is no option similar to 'Edit Town' on the X360/PS3. This means that, except for what is done by story progression, the town will remain the same. You have one family, and if you wish to kick a sim out, you'll have to delete him/her. I'm sorry, but I'm yet to find a work-around.
If you try to move one part out, you can choose to follow the mover, which will delete the remaining part.