diff --git a/debian/ngcp-ngcpcfg.postinst b/debian/ngcp-ngcpcfg.postinst
index 39bb18d5..98ab0148 100644
--- a/debian/ngcp-ngcpcfg.postinst
+++ b/debian/ngcp-ngcpcfg.postinst
@@ -14,6 +14,11 @@ case "$1" in
       fi
 
       addgroup --system --force-badname --quiet _ngcp-admin
+
+      # Since mr10.5.
+      rm -f /etc/ngcp-config/config.yml.factory_default
+      rm -f /etc/ngcp-config/network.yml.factory_default
+      rm -f /etc/ngcp-config/systems.cfg
     ;;
 
     abort-upgrade|abort-remove|abort-deconfigure)