Note: this information applies to Jet Essentials 2015 Update 1. For Jet Essentials 2015, see this article
Typically, upgrading Jet Reports and the Jet Service Tier simply involves running the installation program for the latest release. That installation program is then able to uninstall any out-of-date components and replace them with new versions.
Occasionally, however, new features in an installation program require that older versions of certain components be uninstalled before running the new installer. When this is the case, a special notice is added to the release notes for the latest release.
You will want to remove the components for the Jet Service Tier, without removing Jet Essentials itself.
From the Windows start menu, select Control Panel
You next step depends on which Control Panel view you are using:
If using the "Category" view, select "Uninstall a program" If using one of the "Icon" views, select "Programs and Features"
From the Programs and Features window, select Jet Reports and then click Change near the top of the window.
On the Jet Setup window, select the Modify option and then click the Next button.
On the next screen, leave Jet Essentials as-is, but uncheck all other components.
Once complete, you can proceed with installing the latest version of the Jet Service Tier.