how can i delete a taskinstance from my database

[galvino]

Hi, i want to delete a taskinstance by using its Id.

i used thi:

graphSession=jbpmContext.getGraphSession();
 TaskInstance taskInstance=jbpmContext.getTaskInstance(taskInstanceId);
 TaskMgmtInstance taskMgmtInstance=graphSession.getProcessInstance(processInstanceId).getTaskMgmtInstance();
 taskMgmtInstance.removeTaskInstance(taskInstance);

but it doesn't delete this instance from my database