[ONOS-5954] FloatingIpListener cannot be removed in VTN app. - FloatingIpManager

Change-Id: I389e79dc40d862b8bce1021c4556af1df7e79601
diff --git a/apps/vtn/vtnrsc/src/main/java/org/onosproject/vtnrsc/floatingip/impl/FloatingIpManager.java b/apps/vtn/vtnrsc/src/main/java/org/onosproject/vtnrsc/floatingip/impl/FloatingIpManager.java
index a8b4edf..882f7f9 100644
--- a/apps/vtn/vtnrsc/src/main/java/org/onosproject/vtnrsc/floatingip/impl/FloatingIpManager.java
+++ b/apps/vtn/vtnrsc/src/main/java/org/onosproject/vtnrsc/floatingip/impl/FloatingIpManager.java
@@ -246,7 +246,7 @@
     @Override
     public void removeListener(FloatingIpListener listener) {
         checkNotNull(listener, LISTENER_NOT_NULL);
-        listeners.add(listener);
+        listeners.remove(listener);
     }
 
     /**