It looks like you're running into an existing bug, which can be found here:
The workaround, in this case, is to manually delete the files:
1. Schedule downtime
2. Backup Jira
3. Stop Jira
4. Navigate to JIRA_HOME/plugins/installed-plugins directory
5. Delete/Remove out all jira-servicedesk*.jar or servicedesk* files, depending on what application you're looking to uninstall.
6. Start JIRA
Please be sure to watch it, so that you are notified when this is fixed in a future release.
We know that great teams require amazing project management chops. It's no surprise that great teams who use Jira have strong project managers, effective workflows, and secrets that bring planning ...