postrm is in web2ldap 1.1.43~dfsg-1.
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 | #!/bin/sh
set -e
if [ "$1" = "remove" ] || [ "$1" = "purge" ] ; then
    CONF="web2ldap-fcgid"
    if [ -e /usr/share/apache2/apache2-maintscript-helper ] ; then
        . /usr/share/apache2/apache2-maintscript-helper
        apache2_invoke disconf $CONF
    elif  dpkg-query -f '${Version}'  -W 'apache2.2-common' > /dev/null 2>&1 ; then
        [ -L /etc/apache2/conf.d/$CONF.conf ] && rm /etc/apache2/conf.d/$CONF.conf || true
    fi
fi
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