diff --git a/internal/controller/datamovementmanager_controller.go b/internal/controller/datamovementmanager_controller.go
index 2871bb16..0c145712 100644
--- a/internal/controller/datamovementmanager_controller.go
+++ b/internal/controller/datamovementmanager_controller.go
@@ -130,6 +130,50 @@ func (r *NnfDataMovementManagerReconciler) Reconcile(ctx context.Context, req ct
 		return ctrl.Result{}, err
 	}
 
+	if !manager.GetDeletionTimestamp().IsZero() {
+		log.Info("Deleting DataMovementManager...")
+
+		if !controllerutil.ContainsFinalizer(manager, finalizer) {
+			return ctrl.Result{}, nil
+		}
+
+		// Need to remove the namespace from lustrefilesystem resources
+		if err := r.removeLustreFileSystemsNamespace(ctx, manager); err != nil {
+			return errorHandler(err, "remove all LustreFileSystems namespace spec")
+		}
+
+		// And the finalizer
+		if err := r.removeAllLustreFileSystemsFinalizers(ctx, manager); err != nil {
+			return errorHandler(err, "remove all LustreFileSystems finalizers")
+		}
+
+		// Now it's safe to proceed
+		controllerutil.RemoveFinalizer(manager, finalizer)
+		if err := r.Update(ctx, manager); err != nil {
+			if !apierrors.IsConflict(err) {
+				return ctrl.Result{}, err
+			}
+
+			return ctrl.Result{Requeue: true}, nil
+		}
+
+		return ctrl.Result{}, nil
+	}
+
+	// Add the finalizer if it doesn't exist
+	if !controllerutil.ContainsFinalizer(manager, finalizer) {
+		controllerutil.AddFinalizer(manager, finalizer)
+		if err := r.Update(ctx, manager); err != nil {
+			if !apierrors.IsConflict(err) {
+				return ctrl.Result{}, err
+			}
+
+			return ctrl.Result{Requeue: true}, nil
+		}
+
+		return ctrl.Result{}, nil
+	}
+
 	if err := r.createSecretIfNecessary(ctx, manager); err != nil {
 		return errorHandler(err, "create Secret")
 	}
@@ -341,8 +385,7 @@ func (r *NnfDataMovementManagerReconciler) updateLustreFileSystemsIfNecessary(ct
 	}
 
 	for _, lustre := range filesystems.Items {
-		_, found := lustre.Spec.Namespaces[manager.Namespace]
-		if !found {
+		if _, found := lustre.Spec.Namespaces[manager.Namespace]; !found {
 			if lustre.Spec.Namespaces == nil {
 				lustre.Spec.Namespaces = make(map[string]lusv1beta1.LustreFileSystemNamespaceSpec)
 			}
@@ -366,6 +409,51 @@ func (r *NnfDataMovementManagerReconciler) updateLustreFileSystemsIfNecessary(ct
 	return nil
 }
 
+// Remove nnf-dm namespaces from the spec in all LustreFileSystem resources
+func (r *NnfDataMovementManagerReconciler) removeLustreFileSystemsNamespace(ctx context.Context, manager *nnfv1alpha1.NnfDataMovementManager) error {
+	filesystems := &lusv1beta1.LustreFileSystemList{}
+	if err := r.List(ctx, filesystems); err != nil && !meta.IsNoMatchError(err) {
+		return fmt.Errorf("list lustre file systems failed: %w", err)
+	}
+
+	for _, lustre := range filesystems.Items {
+		if _, found := lustre.Spec.Namespaces[manager.Namespace]; found {
+			delete(lustre.Spec.Namespaces, manager.Namespace)
+
+			if err := r.Update(ctx, &lustre); err != nil {
+				return err
+			}
+			log.FromContext(ctx).Info("Removed LustreFileSystem namespace from the spec", "object", client.ObjectKeyFromObject(&lustre).String(), "namespace", manager.Namespace)
+		}
+	}
+
+	return nil
+}
+
+// Remove nnf-dm finalizers from all LustreFileSystem resources
+func (r *NnfDataMovementManagerReconciler) removeAllLustreFileSystemsFinalizers(ctx context.Context, manager *nnfv1alpha1.NnfDataMovementManager) error {
+	filesystems := &lusv1beta1.LustreFileSystemList{}
+	if err := r.List(ctx, filesystems); err != nil && !meta.IsNoMatchError(err) {
+		return fmt.Errorf("list lustre file systems failed: %w", err)
+	}
+
+	for _, lustre := range filesystems.Items {
+		if controllerutil.ContainsFinalizer(&lustre, finalizer) {
+			controllerutil.RemoveFinalizer(&lustre, finalizer)
+			if err := r.Update(ctx, &lustre); err != nil {
+				return err
+			}
+			log.FromContext(ctx).Info("Removed LustreFileSystem finalizer", "object", client.ObjectKeyFromObject(&lustre).String(), "namespace", manager.Namespace)
+		}
+	}
+
+	return nil
+}
+
+// Check if any LustreFileSystem resources are in the process of being deleted. If they are, that
+// means the DaemonSet is going to restart all the pods to unmount that LustreFileSystem. Wait until
+// the DaemonSet has done that, and then finally remove the finalizer from the LustreFileSystem
+// resource to signal that it's ok to clean up the PV/PVC (since the worker pods are done with it).
 func (r *NnfDataMovementManagerReconciler) removeLustreFileSystemsFinalizersIfNecessary(ctx context.Context, manager *nnfv1alpha1.NnfDataMovementManager) error {
 	log := log.FromContext(ctx)