The FME Flow interface allows for custom System Cleanup Tasks to be created but there is currently no way to trigger these tasks to run manually.
Instead, you need to wait for the automated scheduler to reach the time period defined for the Normal Conditions Task Interval, which is 1 Day by default:
Being able to trigger a task manually would be very useful when creating a custom task as it would allow for rapid testing to ensure the task is correctly defined and working as expected.
Please add the ability to manually trigger a cleanup task.