How to Go to Orgrimmar from Undercity

Go to the Zeppelin towers. The zeppelin towers have zeppelins that shuttle back and forth to various locations in the vast Horde territories. You are going to see two towers there. For Orgrimmargo to the platform at the west edge of the tower (make sure the NPC's name is Zapetta)

You are going to see two towers here. Go inside the building straight to the roof.
make sure the NPC's name is Zapetta