While tasks technically are one of two statuses; open or closed, there are features that can imply a different status to either convey information to users or to lock the task from further edits.

When a task is created, it is set to an open status by default. Most users will have the necessary permission to close tasks and this can be done at any time. I practice, tasks are closed after completing all of the applicable work, and by the individual user that completed the work.

Tasks are closed by clicking the Save & Close button at the bottom of the task activity tab.

Once a task is closed, the button will change to Save & Open. A re-opening of a task will be logged on the activity feed

Re-opening and then re-closing a task will impact historical reports. For example, if materials were consumed in the tasks, those materials will be reported as being consumed on the most recent task close date. Therefore, if a task is re-opened and then re-closed, the consumption date will shift, and could then appear in a different reporting period. If such a shift will cause internal reporting issues, consider using tasks approval, which will lock the status of tasks, yet still allow administrator users to make minor, tracked updates, without the need to re-open and/or re-close the task.

For data protection reasons, tasks can't be deleted, they can only be closed.

If a task is no longer required, it's recommended to add a comment to the activity explaining why it's no longer required or being closed with no other data, for the reference of future users.

Alternatively, you can repurpose the task by simply modifying the title and/or asset, as appropriate, via the three-dot menu that's located near the top right of the screen when inside a task.