I cannnot delete the values from a hash. For example, If I already processed New York City, I want to remove New York City from the hash. Can someone help? I was going to add a new value and set it to 1 for the cities I printed/ processed. The code below does not work and I don't know why. 
my $location_hash = get_location(\*ZIPS);
my $cat_hash = get_categories (\*SICS);

for my $city ( keys %$location_hash ) {
   printf "%s %s %s\n", $city, $location_hash->{ $city }->{ 'ST' }, $l
+ocation_hash->{ $city }->{ 'ZIP' } ;

   for my $cat ( keys %$cat_hash) {
      printf "%s %s\n", $cat, $cat_hash->{ $cat }->{ 'NUM' } ;
      .
      .
      .

      delete ($location_hash->{ $city }) ;            ###  This is wha
+t I want.... Does not work
      delete ($location_hash->{ $city }->{ 'ZIP' } ); ###  Does not wo
+rk
      delete ($cat_hash->{ $cat }->{ 'NUM' });        ###  Does not wo
+rk
      delete ($cat_hash->{ $cat });                   ###  This is wha
+t I want.... Does not work

   } # for my $cat ( keys %$cat_hash)
} # for my $city ( keys %$location_hash ) {

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In reply to How can I delete a key' value from a hash by kevyt

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