#!/usr/bin/perl

use strict;
use warnings;

my $text = do { local $/; <DATA> };

$text =~ s/\/begin blubber.*\/end blubber\n//s;

print $text;

__DATA__
Text
am
Anfang
/begin blubber skdjflkdsjf
sdlkfjdsk
lksjflksdj
aajjllja
/end blubber
Text
am
Ende