• Single group: open it and click the red Delete button in the header; confirm "Are you sure you want to delete this plans group? Your data will be lost".
• Several groups: on the groups list tick the checkbox in the first column of each row (or the header checkbox for the whole page), then click the Remove button that appears above the table and confirm "Are you sure you want to remove N plans groups?".

Deletion is a soft delete: the group is marked deleted and inactive and disappears from all lists. Plans that belonged to it are not deleted, but they no longer appear under any group; assign them a new group or they will not be shown to customers.