Click on the Trash menu on the top right corner of GUI, next to <User Name>, to view the list of drop-down options and then click on Topologies to access list of all deleted network topologies. As shown in the figure.
To restore deleted network topology, click on Restore button; pop-up is displayed asking confirmation on restore action, if the network topology is to be restored, then click on Ok button. Corresponding network topology gets restored.
If there is no need to restore network topology, then click on Cancel button. Corresponding network topology does not get restored.