If for some reason you require to uninstall OSLC Connect for Jira from your Jira instance, you just need to follow the official documentation as for any other plugin.
Be confident data created through OSLC Connect for Jira will be kept in Jira database. Users will still be able to see and navigate the Collaboration Links after uninstalling the connector. They won't be able to preview remote artifacts behind them nor creating new links. Removing Collaboration Links after uninstalling the connector is still possible, but this won't remove the remote back-link on the CLM application.
In the case Jira project administrators were using global configurations, you need to ask to the CLM LDX administrator to remove the datasource created for OSLC Connect for Jira . In the case Jira project administrators were using Jazz Reporting Service and/or RELM, you need to ask to the CLM LQE administrator as well to remove the datasources created for OSLC Connect for Jira .