The method you are referring to belongs to the Annotation object. According to the documentation, you need the name of the style to delete (which it sounds like you already have). Also, this method returns a Boolean value, so you will need to assign some Boolean value to its output.
In order to use it, it sounds like you will have to loop through all annotations in your document and call this method. I am not sure if this will keep the note or not, or which is your goal, but you might also want to look at GetStyleName. This will let you check if the Annotation's style matches the one you want to delete.