How to best clean old Perl installations directories

[Rodolfo Aramayo]

I upgraded Perl from Perl 5.12 to 5.14, activated perl 5.14 and
installed all my perl modules as 5.14

Question:

Inside:
/opt/local/lib/perl5/
I have the following directories:

5.12.2/
5.12.3/
5.12.4/
5.14.2/
5.8.9/
site_perl/
vendor_perl/

Why where the Perl 5.12 directories not removed?
Is there a safe way or proper way to removed these directories?

Thanks

--R