Stuck with a growing pop of a species that is no longer present on the planet

Apparently this bug is still present as of 1.1. If you're not concerned about achievements, you can use console to kill it:

• open console with ~

• type debugtooltip to enable additional info on tooltips

• find ID of the pop by hovering mouse over it, should be at the bottom of the popup

• type kill_pop <ID> into console

If a planet is allowed to go into starvation, any growing pops instead gain a negative growth modifier. When their total growth hits zero, the potential pop will disappear.

The easiest way to get starvation quickly is to disable all your food production buildings, but be aware that starvation is only calculated on a new month.

You will get a -65% happiness modifier while your pops are in starvation mode, and that will also not go away until a new month rolls over.