#!/usr/bin/perl -wT
use strict;

my $line = "I like 'balls' and 'rings', do you like 'rings' and 'balls'?";
print "Before = $line\n";
$line =~ s/(balls|rings)//g;
print "After  = $line\n";

=output
Before = I like 'balls' and 'rings', do you like 'rings' and 'balls'?
After  = I like '' and '', do you like '' and ''?