Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
ob-littĕrātor (oblīt-), ōris, m. [oblittero], a blotter out, obliterator, sc. from the memory (eccl. Lat.): commemorator, non oblitterator vetustatum, Tert. adv. Marc. 4, 26 fin.; Paul. Nol. Ep. 16, 7.