To delete a style from EndNote:
You can also delete an unwanted style by switching back to the Windows desktop, and opening the appropriate Styles folder (see Folder Locations Preferences). Then, select the file to delete and select Delete from the File menu, or drag the file to the Recycle Bin.
Note: You must have read/write access to the Styles folder in order to delete a style. If you do not have administrator access, you likely will not be able to delete a file located within the Program Files folder.