postrm is in dpm-name-server-mysql 1.8.7-3.
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 | #!/bin/sh
set -e
if [ "$1" = "purge" ] ; then
	update-alternatives --display dpnsdaemon > /dev/null || \
		update-rc.d dpnsdaemon remove >/dev/null || exit $?
fi
 |