To delete a system please navigate to WebApp -> Server Admin -> Configuration -> organization / site / agent group and select the 'Edit' button from the bottom of Agent Group screen

While in the Agent group select the Systems tab and click on the Remove button to delete the system

Systems can also be deleted from the "Account > Manage systems" section of the Web App, by clicking on the Bin icon highlighted below.

In this section, the User can also view the "Last Seen Online" timestamp of each device, thus enabling the User to delete systems that have not come online for a substantial period of time.

Note: that the system, which are you deleting should be online at the time when are you deleting it, because if the system is offline at that time, then the reconfigure command will not be sent to that system and that system will re-register with our account as soon as it will come back online. However if the system no longer exists, then simply delete it.