DELETE FROM provisioning.voip_preferences_enum WHERE preference_id = 
  (SELECT id FROM provisioning.voip_preferences WHERE attribute = 'sst_enable');
DELETE FROM provisioning.voip_preferences_enum WHERE preference_id = 
  (SELECT id FROM provisioning.voip_preferences WHERE attribute = 'sst_refresh_method');
DELETE FROM provisioning.voip_preferences where attribute = 'sst_enable';
DELETE FROM provisioning.voip_preferences where attribute = 'sst_refresh_method';
DELETE FROM provisioning.voip_preferences where attribute = 'sst_expires';
DELETE FROM provisioning.voip_preferences where attribute = 'sst_min_timer';
DELETE FROM provisioning.voip_preferences where attribute = 'sst_max_timer';