code: void removeEdgeLabel(EdgeLabel edgeLabel, boolean preserveData) {
          getTopology().lock();
          String fn = this.name + "." + EDGE_PREFIX + edgeLabel.getName();
  
          if (!uncommittedRemovedEdgeLabels.contains(fn)) {
              uncommittedRemovedEdgeLabels.add(fn);
              TopologyManager.removeEdgeLabel(this.sqlgGraph, edgeLabel);
              for (VertexLabel lbl : edgeLabel.getOutVertexLabels()) {
                  lbl.removeOutEdge(edgeLabel);
              }
              for (VertexLabel lbl : edgeLabel.getInVertexLabels()) {
                  lbl.removeInEdge(edgeLabel);
              }
  
              if (!preserveData) {
                  edgeLabel.delete();
              }
              getTopology().fire(edgeLabel, "", TopologyChangeAction.DELETE);
          }
      }
docs: remove a given edge label
  
  @param edgeLabel    the edge label
  @param preserveData should we keep the SQL data