(automatically) delete ALL completed reminders?

Hi,

in previous versions of iCloud it was possible to delete all completed reminders at once.

Gone these days :-(

Why?

Anyone having a tip how to delete ALL completed reminders at once ?

I want to do this, because:

1) If this pile of completed reminders grows to big it hinders iCloud sync.

2) It's a growing data garbage pile and that's never good.

This is not device specific, so never mind the Apple requirement to select a device.