The hash looks something like:
$global{'title'}='Report for today'
$global{'data 1'}{title}='My data 1 title'
$global{'data 1'}{data}= (ref to hash)
$global{'data 1'}{footer}='My footer'
$global{'data 2'}{title}='My data 2 title'
$global{'data 2'}{subtitle}='Data 2 subtitle'
$global{'data 2'}{data}= (ref to hash)
$global{'data 2'}{'data percentages'}= (ref to hash)
$global{'data 2'}{'data raw'}= (ref to hash)
$global{'data 2'}{footer}='Footer for data 2'
and so on..

##</code><code>##

sub hash_remove_key_space
{	my $in_hash = shift;
	my %work_hash = %$in_hash;
	my %output_hash;	
	foreach my $ckey(keys %work_hash){
		my $value;
		if (ref($work_hash{$ckey}) eq "HASH") 
			{
			$value = hash_remove_key_space($work_hash{$ckey});
			}
		else	{
			$value = $work_hash{$ckey};
			}
		my $temp = $ckey;
		$temp =~ s|\s||isg;
		$output_hash{$temp} = $value;
		}				
	return \%output_hash;		
}

corrected code - per Sam