The timesheet has what we like to call a "magic algorithm". It adds tasks to your timesheet that are scheduled in the near future, plus anything you logged time to recently and did not mark done (ie last week), and anything you manually added.

If you have a task that is there with logged time, you can clear the logged time and it will go away if it is not scheduled to be worked on soon. You can also move the task out to a later date on the schedule or even put the task on hold; that will likely take it off your timesheet. Taking the time to estimate tasks will also spread your work out over time and de-clutter your timesheet.

We've talked about an explicit remove from timesheet, but we keep coming back to the idea that it's there because it's scheduled to be there.

We are aware that sometimes too many things show up on the timesheet and it becomes a bit unwieldy; we're thinking about that.

Agreed, I'll add it as a feature request for the LP development team. Thanks Donald.