Starting in TIBCO Spotfire 10.0, clustering is implemented using Apache Ignite, and clustering is enabled in all Spotfire environments by default. This is also applicable for environments with just single a Spotfire Server, either a new installation or an upgrade from previous versions where clustering was not enabled. Upgrading to TIBCO Spotfire 10.0 or later versions automatically switches to the Apache Ignite method, no matter if clustering was enabled in previous versions or not. 

This article explains if it is possible to disable clustering manually for environments with a single TIBCO Spotfire Server after installation or upgrade.

Having clustering enabled by default is as-designed and this is also applicable for Spotfire environments with just a single TIBCO Spotfire Server. It is NOT possible to disable clustering.

The Spotfire Server Configuration Tool (\tomcat\bin\uiconfig.bat or tomcat\spotfire-bin\uiconfig.bat) does not give that option, and the config-cluster command ignores values of the --enabled flag. If the configuration property is added manually in Spotfire Server configuration file (configuration.xml) to disable clustering, it will be ignored by Spotfire Server.
 

This article explains if it is possible to disable clustering manually for environments with a single TIBCO Spotfire Server after installation or upgrade to 10.0 and higher.

Doc: Spotfire server 10.0 Release notes

• https://docs.tibco.com/pub/spotfire_server/10.0.0/TIB_sfire_server_10.0.0_relnotes.pdf?id=2