I was building a mob zoo and my bats got out and they fly around and annoy me. How do i remove them?
According to the Wiki bats will spawn in areas below layer 63, with a light level of 7 or less. So, much like you would to prvent hostile mobs from spawning, light area with torches (or whatever your preferred source of light is).
To get rid of them, kill them in any conventional way (swords, arrows, splash potions, fire). They are passive and will not attack you even if you hit them.