The Release function is only available for Worklist Items with an "Open" status. When a user opens a Worklist Item, they take up one of the available "Slots" for that task. Suppose a task is allocated to two users (Bob and Alice), and there is only one Slot available for that task. As soon as Bob opens the task, the task item's status changes to "Open" for Bob and "Allocated" for Alice, and Alice will not be able to open the task anymore because there was only one available slot, which was "taken" by Bob. Releasing the Worklist Item resets the item's status back to "Available" so that either of the two users (Bob or Alice) can open the Worklist Item.
You can also use the Release option on tasks allocated to roles (but only if the Resolve groups to individuals option in the workflow task result configuration is unchecked). Only K2 Administrators and Process Administrators can release task list items assigned to a role. Suppose a task is allocated to role called Finance, and the role contains users (Bob and Alice). As soon as Bob opens the task, the task's status changes to "Open" for Bob and "Allocated" for Alice. When you want to release the task, the Role Members page opens and displays all the users in the role. In this scenario, Bob's task item status is "Open". To release the task back to the members in the role, select Bob and click Release. This resets the task's status back to "Available" so that either of the two users in the role (Bob or Alice) can open the task. You can also view the members of a role by clicking the Role Members option. For more information see the Role Members section.
Release a Task Assigned to a User or Group
Follow these steps to release a task list item that is assigned to a user or group:
- Select the task list item you want to release. If the Status of the item is Open, the Release button becomes available.
- Click Release.

- Click OK on the confirmation message.
- The task list item's status will change to Available, indicating that the task is available for any member in the group to open.
Release a Task Assigned to a Role
Follow these steps to release a task list item assigned to a role:
- Select a task list item that is assigned to a role. If the Status of the item is Open, the Release button becomes available.

If you do not see a role listed in the
Destination column, the
Resolve groups to individuals option is most likely enabled in the workflow definition, and you will not be able to use the Role Members page as described here.
- On the Role Members page, select the user in the role who has the task list item open, and click Release.

- Click OK on the confirmation message.
- The task list item's status changes to Available, and the task is available for any member in the role to open.