drop
How to drop a graph.
Synopsis
system.graph('graph_name').[ifExists()].drop()
    Description
Drop an existing graph using this command. All data and schema will be lost. For better performance, truncate a graph before dropping it.
Examples
Drop a
        graph.
      system.graph('FridgeItem').drop()The
        resulting list:==>nullDrop an existing graph if it
        exists.
    system.graph('FridgeSensors').ifExists().drop()The
        resulting list:==>null