Something like this?

use strict;
use warnings;

chomp(my @title = split /\s+/, <DATA>);

my %emp;
while (<DATA>) {
    chomp(my @r = split/\s+/);
    push @{$emp{$r[0]}}, [ @r[1..$#r] ];
}

foreach (reverse sort keys %emp) {
    print "$_";
    foreach (@{$emp{$_}}) {
        print "\t$_->[0]\t$_->[1]\n";
    }
}

__DATA__
EmpNum  LOCATION  Shift
23        54        1
11        65        3
23        54        2
[download]

And the output -

23      54      1
        54      2
11      65      3
[download]

Updated: solution 2

use strict;
use warnings;
use Data::Dumper;

chomp(my @title = split /\s+/, <DATA>);
chomp(my @data = <DATA>);

my @sorted_data =
    map { $_->[1] }
    sort { $b->[0] <=> $a->[0] }
    map { [/^(\d+)/, $_] } @data;
    
my $last_emp = '';
foreach my $d (@sorted_data) {
    $d =~ s/^$last_emp\b/' ' x length($last_emp)/e;
    $d =~ /^(\d+)/ and $last_emp = $1;
    print "$d\n";
}


__DATA__
EmpNum  LOCATION  Shift
23        54        1
11        65        3
23        54        2
[download]