If you need to reschedule an interview, you can do so from within the candidates profile, under the Interviews tab, or from the list of candidates found in the Interview's hiring workflow stage

Once you click this button you can select whether you want the candidates to pick the time to reschedule or if you pick the new time that works better for everyone.

This video shows you what it looks like: https://www.loom.com/share/a1740c31b1c249ba8be272e4c6974e4b