In line with what JMD said:

sub delete_field
{
     my $self      = shift;
     my ($deleter) = @_;
     my $scrubbed  = 0;

     @{$self->{_fields}} =
        grep { !(($deleter eq $_) && ++$scrubbed) }
             @{$self->{_fields}};
 
     return $scrubbed;                
}
[download]

Which is really just evaluating a match/mismatch case, but with some intermediate code to increment $scrubbed.