postrm is in crawl-common 2:0.10.3-3.
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 8 9 10 | #!/bin/sh
set -e
# Applies only to versions <0.8
if [ "$1" = "purge" ]; then
    echo -n "Purging high scores and bone files for Crawl... "
    rm -rf /var/games/crawl/
    echo "done."
fi
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