How does banning robot workers work? Am I doing something wrong?

I'm playing my first game now, and I've got an empire that controls most of the galaxy. I decided to outlaw robot workers. The tooltip said that this will:

• Stop new robots from being made (this has happened)
• Automatically remove robot armies (this has also happened)
• Automatically disassemble existing robots (this has not happened)

Am I missing something in regard to the last bullet point? The policy has been in effect for about a year and the robot population has not gone down at all.