In general, we assume that you are managing installation of ictime via the Universal PlugIn Manager (UPM) of JIRA.
Deactivate
In JIRA, go to
Administration -> Plugins -> Manage my plugins
Look for ictime, click on it and click on the "Deactivate" button.
Uninstall
Warning: Allthough you are not going to loose your work logs, as they are stored in the JIRA database, you might loose all additional data and configuration managed by ictime for all work logs when uninstalling the plugin, especially all financial information, all invoices, activity type assignments, teams and team assignment etc. There is no undo.
In JIRA, go to
Administration -> Plugins -> Manage my plugins
Look for ictime, click on it and click on the "Uninstall" button.