Unfortunately, you are going to clobber middle initials as well :-(

knoppix@Microknoppix:~$ perl -E '
> $name = q{John I. Jones, IV};
> say $name;
> $name =~ s{\b[IVXLCDM]+\b}{}g; 
> say $name;'
John I. Jones, IV
John . Jones, 
knoppix@Microknoppix:~$
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Perhaps doing something to remove the comma as well and making the assumption that you can anchor to the end of string?