Assuming you are using the desktop version of Endnote.
There are often other specifics to a style than just numbered in text citations and order in bibliography. So accurate advice would need to be targeted publication specific.
But Vancouver is a style that can be easily modified to alphabetical order, by editing it to select one of the alph ordered options (bibliography >sorting as shown in the image) – save as to a new name, and then use that newly named output style on the Endnote ribbon in your word document.
