One can install and --uninstall, but there is no --list option.

E.g., one should be able to do
cpanm --list to get a list of names that would each then be valid for
use with --uninstall.

$ instmodsh
Available commands are:
   l            - List all installed modules
   m <module>   - Select a module
   q            - Quit the program
cmd? l
Installed modules are:
   Algorithm::GooglePolylineEncoding
   Algorithm::Loops
   App::pmuninstall
   AppConfig
   CPAN::Meta
   CPAN::Meta::YAML
   Carp::Clan
   Class::Accessor
   Class::Data::Inheritable
   Class::Default
   Data::Dump
   Data::JavaScript::Anon
   Encode::Repair
   ExtUtils::MakeMaker
   HTML::Selector::XPath
   JSON::PP
   MRO::Compat
   Module::Metadata
   Module::Pluggable::Fast
   MozRepl
   Net::Telnet
   Object::Import
   Params::Util
   Perl
   Perl::OSType
   Shell::Command
   Spiffy
   Task::Weaken
   Template
   Template::Provider::FromDATA
   Test::Base
   Text::SimpleTable
   UNIVERSAL::require
   Version::Requirements
   WebService::GData
   YAML
cmd? q
$ cpanm -U JSON::PP
invalid top directory at /usr/share/perl/5.20/File/Find.pm line 472.
$ find perl5 -name PP
perl5/lib/perl5/i486-linux-gnu-thread-multi/auto/JSON/PP
perl5/lib/perl5/JSON/PP
$ pwd
/home/jidanni