[VOL-3767] Allow the removal of a specific device in DeviceRules

Change-Id: If282dbf3dd4067e9556a4799b3d9430574867c9e
diff --git a/pkg/flows/flow_utils.go b/pkg/flows/flow_utils.go
index 41b615a..1e50a63 100644
--- a/pkg/flows/flow_utils.go
+++ b/pkg/flows/flow_utils.go
@@ -1378,6 +1378,12 @@
 	return filteredDR
 }
 
+func (dr *DeviceRules) RemoveRule(deviceId string) {
+	dr.rulesLock.RLock()
+	defer dr.rulesLock.RUnlock()
+	delete(dr.Rules, deviceId)
+}
+
 func (dr *DeviceRules) AddFlow(deviceId string, flow *ofp.OfpFlowStats) {
 	dr.rulesLock.Lock()
 	defer dr.rulesLock.Unlock()