prerm is in ledit 2.03-2build1.
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 | #!/bin/sh
set -e
if [ "$1" != "upgrade" ]; then
  update-alternatives --remove readline-editor /usr/bin/ledit
fi
 |