#!/usr/bin/perl -w
use strict;
use Data::Dumper;
$Data::Dumper::Useqq = 1;

$_ = join '', <DATA>;

print "\nBefore: ", Dumper($_);
$_ =~ s/<IT>\s*<\/IT>//gi;
print "\nAfter:  ", Dumper($_);

__DATA__
Foo<iT></It>Bar
Baz<it>!</it>Qux


##</code><code>##

Before: $VAR1 = "Foo<iT></It>Bar\nBaz<it>!</it>Qux\n";
After:  $VAR1 = "FooBar\nBaz<it>!</it>Qux\n";