This is the expected autovivification behaviour in Perl that you should be aware of. That's why you should check the existance of a key and its ancestors' keys before deleting it.

exists $info{'level_b'} and
  exists $info{'level_b'}{2} and
    exists $info{'level_b'}{2}{'name'} and  # this line is not necessa
+ry
      delete $info{'level_b'}{2}{'name'} or warn $!;
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I did a super-search and found the following node ... Autovivification with hash of hashes ... that addresses this problem.

PS: That print Dumper(%info); could be better written as print Dumper(\%info); to give a cleaner presentation of the data structure.