To rename a changelist
  1. Select a changelist in the Version Control Tool Window.
  2. On the context menu, choose Rename Changelist.
  3. In the Edit Changelist dialog, specify the new name and optional description, and click OK.

Alternatively, use the ⇧F6 or ⇧F6⇧F6 or ⇧F6⇧F6 or ⇧F6⇧ F6, ⇧F6 or ⇧F6⇧ F6, ⇧F6 or ⇧F6 keyboard shortcut.