Mark Tasks as Inactive or Hidden

Thinking out loud......

1. Once one person accepts a task assigned to a group, it will be removed from other's task list
2. You could add a button to your tasks that 'submits' the task and populates a PV or two that set a flag and who 'owns' it. Then route the flow back to the task. Now in the process reports, apply a filter to not show tasks with the PV (flag=true)

This is not so much for reporting as to remove it from the Task List of the user (or all users in a group, if it is assigned to a group). I suppose creating a "hidden user" and assigning to that user would functionally hide it from everyone else, other than the manager I suppose. I was hoping for something more elegant, but I could use that as a fallback.

Depending on your use case, you may also be able to utilize the Pause Processes / Resume Processes services via a separate management process. Pausing a process will remove it from all assignees tasks list, resuming will add it straight back.

I actually did not know that Paused processes removed it from the assignees' task list. This is likely exactly what I was looking for.