So something more like:

use strict;
use warnings;

my $wholeBallOfWax = do {local $/; <DATA>};
my @records = split /\s*(?<=\n)(?=\d+~)/, $wholeBallOfWax;

s/\n+/ /gs for @records;
s/\s+\z//gs for @records;

print join "\n", @records;

__DATA__
99~Arun~Kumar~Mobilenum:
1234-567 , from Earth
Human
98~Mahesh~Babu~Mobilenum:
5678-901 , from Earth
Human

97~Grand~Father~Mobilenum:
2734-567 , from Mars
Ape
[download]

Prints:

99~Arun~Kumar~Mobilenum: 1234-567 , from Earth Human
98~Mahesh~Babu~Mobilenum: 5678-901 , from Earth Human
97~Grand~Father~Mobilenum: 2734-567 , from Mars Ape
[download]

where the only substantive change from my suggested earlier code was to replace hyphen with tilda and replace internal newlines with spaces.

Update: or Per Hippo's suggestion:

use strict;
use warnings;
use Test::More tests => 1;

my @want = (
'99~Arun~Kumar~Mobilenum: 1234-567 , from Earth Human',
'98~Mahesh~Babu~Mobilenum: 5678-901 , from Earth Human',
'97~Grand~Father~Mobilenum: 2734-567 , from Mars Ape'
);

my $wholeBallOfWax = do {local $/; <DATA>};
my @records = split /\s*(?<=\n)(?=\d+~)/, $wholeBallOfWax;

s/\n+/ /gs for @records;
s/\s+\z//gs for @records;

is_deeply (\@records, \@want);

__DATA__
99~Arun~Kumar~Mobilenum:
1234-567 , from Earth
Human
98~Mahesh~Babu~Mobilenum:
5678-901 , from Earth
Human

97~Grand~Father~Mobilenum:
2734-567 , from Mars
Ape
[download]