prerm is in inetutils-traceroute 2:1.9.4-1build1.
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 | #!/bin/sh
set -e
case "$1" in
    remove|deconfigure)
        update-alternatives --remove traceroute /usr/bin/inetutils-traceroute
        ;;
    *)
esac
 |