In Questetra BPM Suite, you can abandon a Task that you accepted. "Returning" is the procedure to return the once accepted task back to “offered state” In the other hand, "Delegating" is assigning the task to anyone in particular. Users who have the "Control Authority" on the workflow can forcibly assign the retaining process to anybody else.
In Questetra BPM Suite, there are two methods of abandonment for Tasks in [My Task]. They are "Returning" and "Delegating".
"Returning" Task that you have accepted is a procedure of putting it back to state that it was before you accepted. The Task goes back it was before, the state of offered as 'Would somebody accept?' Yourself can accept it again.
"Delegating" Task that you have accepted is a procedure of allocating it to other User. The task will become the target user's [My Tasks].
User whom you can delegate to is limited to the range that is defined in the process model (allocation rule).
Therefore, you cannot delegate a Task if it is defined as "Nobody else can Process" in the allocation rule of the Process Model Definition.
* Note : Anyone with the authority of control can allocate Tasks to any user ignoring Process Model Definition.