You can always deactivate a JioTune before its 30-day validity. However, you will have to wait for the remaining days before setting a new JioTune as a free account holder. For example, if you deactivate the JioTune on the 27th day*, you will have to wait 3 more days before you can set up a new JioTune. In case you wish to set unlimited JioTune, head to the Pro page in your JioSaavn app to look for the best subscription options.
*Please note that a JioTune is valid only for 30 days unless deactivated by you.