Is there a way of deleting /clearing all of the markers at once?

Go to Views/Markers, highlight them all then hit delete.

CTL-A selects them all. 

Thanks!!!  I was going cross-eyed, trying to select and delete all 25 markers one at a time.
 

Very un-intuitive, the UI design has no knowledge on human computer interaction.

To delete marker you need to:
- find documentation, nothing in the documentation
- go to cakewalk docs website, and search, also nothing
- google "remove marker", then you can get here, and find that alt-shift-F4 to open marker view for sonar.

Cakewalk need to learn from Microsoft Office to make things easier for users. No one should read documentation and go to search engine to find how to delete markers, TL;DR. The context menu should handle it.