revoke assignment

[massimiliano_cuccia]

I have a task assigned to group(administrators)
and i get a TaskInstance and assign the actor to admin1 using this code

ti.setActorId("admin1");

so the task is corrently assigned to the user "admin1" (member of group "administrators")

How do I revoke this assignment?
actually I want that the task goes into original state: assigned to the "administrators" group. Is it possible?

thanks
regards

[kukeltje]

ti.setActorId(null);