The Denodo Diagnostic & Monitoring Tool allows you to close sessions. Check out the [user manual for Diagnostic & Monitoring](https://community.denodo.com/docs/html/browse/8.0/en/vdp/dmt/index) for how to get the Diagnostic & Monitoring Tool set up, and the [Monitoring - Sessions manual](https://community.denodo.com/docs/html/browse/8.0/en/vdp/dmt/monitoring/monitoring_servers/monitoring_sessions) for information about monitoring sessions. Once you have the Diagnostic & Monitoring tool up and running and monitoring VDP sessions, you can right click on the session you want to close and click "Cancel Connection."
Note that in addition to the Denodo Diagnostic & Monitoring tool, 3rd party tools can be used to monitor the VDP servers and close connections if needed, check out the user manual for [Monitoring with Java Management Extentions](https://community.denodo.com/docs/html/browse/8.0/en/vdp/administration/monitoring_the_virtual_dataport_server/monitoring_with_a_java_management_extensions_jmx_agent/monitoring_with_a_java_management_extensions_jmx_agent).
Hope this helps!