You can get the boxes in the selection and remove all comments like this:
IEnumerable<InlineLayoutBox> selectedBoxes =
In this way, all comments that have their start within the selection will be removed. You can further customize this solution to check if the CommentRangeEnd is within the selection instead of CommentRangeStart or check if both the start and end of the comment are within the selection.
However, you should have in mind that each delete operation will be registered separately in the history stack and undo/redo will add/remove only one comment at a time. I hope this helps.
the Telerik team
Explore the entire Telerik portfolio by downloading the Ultimate Collection trial package. Get it now >>