To answer your explicit question: One does it using the Project tool.
ArcToolbox > Data management Tools > Projections and Transformations > Feature > Project
To trouble shoot your issue, it might help to more precisely define "not lining up".
Have you tried going the other way (UTM to geographic)? That might throw some light on matters.
Some times an incorrect UTM zone has been specified somewhere, which can look confusing if one does not know what that looks like...