Reassignment requests can only be initiated by users explicitly assigned the primary workflow role (as a named user). They cannot be submitted for backup roles, or by members of Teams/Groups assigned primary roles.
Assignees and Approvers can dispute a preparer/reviewer assignment on one or more tasks by submitting a request to administrators and power users to reassign the tasks.
From the Task Actions dialog box, workflow users (Assignees and Approvers) can request reassignment of their workflow role for selected or selected and future tasks. These requests require approval. Administrators and schedule/template Owners can still reassign the task using the Edit Task dialog box without requiring approval.
If you do not know the new user, then submit a request without specifying the name of the user.