Everywhere, but specially in bash, cleaning up is annoying and error prone. Resource leaks can be common if your bash script is interrupted half-way. Do you need to execute something always, even if your script fails or gets killed? Try using traps:
#!/bin/bash
foobar() {
echo "See ya!"
}
trap "foobar" EXIT
It doesn't mater how you end this script, "foobar" will always be executed. Want to read more about bash traps? Check here.