How to delete CO number range intervals

Hi,

I copied CO number range interval via transaction code KANK but now I want to delete the number ranges.

There are no movement data or anything else, I just created the controlling area and copied the number ranges.

Unfortunately I do not find the possibility to delete any of the ranges.

I already tried to delete the controlling area but there comes the information that number ranges already exist (object RK_BELEG).

How can I delete the existing number range intervals?

Thank you for any help

Britta