An Administrator can use the "Share" function that can be accessed via the Task List tab of the Process Details page in K2 Management, to share/delegate a task to another user. https://help.nintex.com/en-US/k2five/userguide/5.5/default.htm#K2-Management-Site/Workflow_Server/TaskList.htm

The same functionality is available via either the tasklist in the K2 Workspace or the tasklist control, but in this case the task would need to be shared by the current task user.

thank you for your quick reply.