Perl library locations, and System Integrity Protection

My system perl seems to have a bunch of cruft left over from previous installations: % which perl /usr/bin/perl % perl -V | perl -ne 'print if /INC/...//' @INC: /Library/Perl/5.18/darwin-thread-multi-2level /Library/Perl/5.18 /Network/Library/Perl/5.18/darwin-thread-multi-2level /Network/Library/Perl/5.18 /Library/Perl/Updates/5.18.2/darwin-thread-multi-2level /Library/Perl/Updates/5.18.2 /System/Library/Perl/5.18/darwin-thread-multi-2level /System/Library/Perl/5.18 /System/Library/Perl/Extras/5.18/darwin-thread-multi-2level /System/Library/Perl/Extras/5.18 . Among the stuff in /System/Library/Perl/Extras/5.18/darwin-thread-multi-2level is an old version of Moose.pm that doesn't work, so I want to get rid of it: % perl -MMoose -e1 Invalid version format (version required) at /Library/Perl/5.18/Module/Runtime.pm line 396. BEGIN failed--compilation aborted. % perldoc -l Moose /System/Library/Perl/Extras/5.18/darwin-thread-multi-2level/Moose.pm However, I can't: % sudo rm /System/Library/Perl/Extras/5.18/darwin-thread-multi-2level/Moose.pm Password: override rw-r--r-- root/wheel restricted,compressed for /System/Library/Perl/Extras/5.18/darwin-thread-multi-2level/Moose.pm? y rm: /System/Library/Perl/Extras/5.18/darwin-thread-multi-2level/Moose.pm: Operation not permitted I'm *guessing* that in my various OS updates over the years, Apple has moved some of my user-installed modules to this /System/Library/Perl/Extras directory, but then protected it with System Integrity Protection, so now I can't get rid of it (easily). Does that sound likely? If so - how the heck did this stuff get there? According to https://apple.stackexchange.com/questions/193368/what-is-the-rootless-feature-in-el-capitan-really , any extra junk in /System that Apple didn't want there should have been moved to /Library/SystemMigration/History/Migration-(some UUID)/QuarantineRoot, right? I've never disabled SIP on this machine. So: what's the best way to deal with this? I can temporarily disable SIP and blow away /System/Library/Perl/Extras/5.18 or whatever - but I'd like some assurance that this isn't something Apple actually expects to be there. Is there a definitive list of what should be present in /System on my OS (which is High Sierra, 10.13.4 (17E199))?