diff --git a/pkg/cluster/sync.go b/pkg/cluster/sync.go
index 1c3f73b7f..908806dda 100644
--- a/pkg/cluster/sync.go
+++ b/pkg/cluster/sync.go
@@ -1033,12 +1033,20 @@ func (c *Cluster) syncStandbyClusterConfiguration() error {
 
 		if c.Spec.StandbyCluster.StandbyHost != "" {
 			standbyOptionsToSet["host"] = c.Spec.StandbyCluster.StandbyHost
-			if c.Spec.StandbyCluster.StandbyPort != "" {
-				standbyOptionsToSet["port"] = c.Spec.StandbyCluster.StandbyPort
-			}
-			if c.Spec.StandbyCluster.StandbyPrimarySlotName != "" {
-				standbyOptionsToSet["primary_slot_name"] = c.Spec.StandbyCluster.StandbyPrimarySlotName
-			}
+		} else {
+			standbyOptionsToSet["host"] = nil
+		}
+
+		if c.Spec.StandbyCluster.StandbyPort != "" {
+			standbyOptionsToSet["port"] = c.Spec.StandbyCluster.StandbyPort
+		} else {
+			standbyOptionsToSet["port"] = nil
+		}
+
+		if c.Spec.StandbyCluster.StandbyPrimarySlotName != "" {
+			standbyOptionsToSet["primary_slot_name"] = c.Spec.StandbyCluster.StandbyPrimarySlotName
+		} else {
+			standbyOptionsToSet["primary_slot_name"] = nil
 		}
 	} else {
 		c.logger.Infof("promoting standby cluster and detach from source")
diff --git a/pkg/cluster/sync_test.go b/pkg/cluster/sync_test.go
index 9e2c026e9..e2b242d9d 100644
--- a/pkg/cluster/sync_test.go
+++ b/pkg/cluster/sync_test.go
@@ -819,6 +819,23 @@ func TestSyncStandbyClusterConfiguration(t *testing.T) {
 	// this should update the Patroni config with host, port and primary_slot_name
 	err = cluster.syncStandbyClusterConfiguration()
 	assert.NoError(t, err)
+
+	// test property deletion: remove standby_primary_slot_name
+	cluster.Spec.StandbyCluster = &acidv1.StandbyDescription{
+		StandbyHost: "remote-primary.example.com",
+		StandbyPort: "5433",
+	}
+	cluster.syncStatefulSet()
+	updatedSts5 := cluster.Statefulset
+
+	// check that STANDBY_PRIMARY_SLOT_NAME is not present
+	assert.Contains(t, updatedSts5.Spec.Template.Spec.Containers[0].Env, v1.EnvVar{Name: "STANDBY_HOST", Value: "remote-primary.example.com"})
+	assert.Contains(t, updatedSts5.Spec.Template.Spec.Containers[0].Env, v1.EnvVar{Name: "STANDBY_PORT", Value: "5433"})
+	assert.NotContains(t, updatedSts5.Spec.Template.Spec.Containers[0].Env, v1.EnvVar{Name: "STANDBY_PRIMARY_SLOT_NAME", Value: "standby_slot"})
+
+	// this should update the Patroni config and set primary_slot_name to nil
+	err = cluster.syncStandbyClusterConfiguration()
+	assert.NoError(t, err)
 }
 
 func TestUpdateSecret(t *testing.T) {