I saw above that you said there is a possibility to close several test runs at once using TestRail API.
"If you many test runs/plans to close (e.g. hundreds), you can also look into using TestRail's API to close the runs/plans programmatically (I'm happy to provide the steps in this case)."
Could you help me with that? We have a lot of opened test runs and I planned to implement functionality that will be triggered every week and will close all test runs older than i.e. two weeks. Is that possible?