dis·join 
(dĭs-join)
(dĭs-join)v. dis·joined, dis·join·ing, dis·joins
v.tr.
To undo the joining of; separate.
v.intr.
To become separated.
[Middle English disjoinen, from Old French desjoindre, from Latin disiungere : dis-, dis- + iungere, to join; see JOIN.]