HDEL key field [field ...]
Time complexity: O(N) where N is the number of fields to be removed.
Removes the specified fields from the hash stored at
Specified fields that do not exist within this hash are ignored.
key does not exist, it is treated as an empty hash and this command returns
Integer reply: the number of fields that were removed from the hash, not including specified but non existing fields.
dragonfly> HSET myhash field1 "foo"
dragonfly> HDEL myhash field1
dragonfly> HDEL myhash field2