prerm is in libomxil-bellagio0 0.9.3-3ubuntu1.
This file is a maintainer script. It is executed when installing (*inst) or removing (*rm) the package.
The actual contents of the file can be viewed below.
| 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 | #!/bin/sh -e
case "$1" in
    remove|upgrade|deconfigure)
	rm -f /var/lib/libomxil-bellagio0/registry
    ;;
    failed-upgrade)
    ;;
    *)
        echo "prerm called with unknown argument \`$1'" >&2
        exit 1
    ;;
esac
exit 0
 |