How to remove text using PERL

Suppose i have a variable which pointed towards some string with special character for example : $b="abcdef^bbwk#kdbcd@"; I need a perl script which will open that file delete the first line as per the given example and if possible write them back.

#!/usr/bin/perl

Code:

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$b = "abcdef^bbwk#kdbcd@";
$b =~ s/[^b-zA-Z0-9]*//g;

print $b . "\n";

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Code:

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open(IN,"<perl.txt);
open(OUT,">new_perl.txt");
while (IN)
{
  # if not first line ($.) write current line ($_) to out file
    $. > 1 and print(OUT $_);
}
close(IN);
close(OUT);

# if you want to overwrite the original
rename("new_perl.txt","perl.txt");

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