Do they have the word dictionary in the dictionary?
Likewise, does the dictionary have every word?
Dictionaries do not contain all the words Perhaps because they tend to be rather large books there is frequently an assumption that most dictionaries contain all the words in the language. There has never been, and never will be, a dictionary that includes all the words in English.
Keeping this in view, do they remove words from the dictionary?
As it is the mission of the OED to provide “a permanent record of [a word's] place in the language”, once a word is deemed worthy to be added to the dictionary, as previously noted, it will never be removed, regardless of whether or not it later falls out of use.
However, it is worth noting that words are sometimes missing from the dictionary because they are too new, too specialized, "nonlexical", or otherwise inappropriate for entry into the dictionary.