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 OSLC Remote Application.
In the case Jira project administrators were using IBM Collaborative Lifecycle Management global configurations, you need to ask to the IBM Link Index Provider (LDX) administrator to remove the datasource created for OSLC Connect for Jira . In the case Jira project administrators were using IBM Jazz Reporting Service and/or IBM Rational Engineering Lifecycle Manager (RELM), you need to ask to the IBM Lifecycle Query Engine (LQE) administrator as well to remove the datasources created for OSLC Connect for Jira .