postrm is in libssh2-php 0.12-1build1.
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 | #! /bin/sh
set -e
if test "$1" = "purge"; then
    if which ucf >/dev/null 2>&1; then
        ucf --purge /etc/php5/mods-available/ssh2.ini
    fi
    rm -f /etc/php5/mods-available/ssh2.ini
fi
exit 0
 |