Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
mănūmitto (also as two words, v. infra; and ante-class. manu emitto, v. emitto, I. B.), mīsi, missum, 3, v. a. [1. manus-mitto], to release from one’s power (manus), to set at liberty, to enfranchise, emancipate, make free a slave (v. manumissio): quos (servos) nisi manumisisset, Cic. Mil. 22, 58: sunt servi de cognatorum sententiā manumissi, id. Cael. 29, 68; id. Fam. 13, 77, 3: testamento manumissi, Tac. A. 13, 32: quos proxime inter amicos manumisisti, Plin. Ep. 7, 16, 4.
Separated by other words: orabo, ut manu me mittat, Plaut. Aul. 5, 4: manu vero cur miserit? Cic. Mil. 22, 57: manu non mittere, Liv. 41, 9, 11 fin.