I want to remove the Canada being allied with US option.

[UchihaMadara971]

How do I change the alliances the game already starts with?

[catatonic]

First read this:

http://www.supremewiki.com/index.php/Map_.CSV_Data

To break the U.S.-Canada alliance:

1) go to folder CAMPAIGNGC.
2)Open the .CSV file that corresponds to the campaign that you want to modify.
3)Locate the &&CVPREL section for Canada (ID#2499):

&&CVPREL 2499 //

4)Scroll down until you find the ID number for the U.S. - 2999:

2999 1 -0.05 -0.2

5)Delete this line or comment it out with a leading "//".
6) Repeat steps 3,4, and five above for the U.S.'s CVPREL section.
7) Save your work and close the file.
8) Rebuild the campaign's cache,

[georgios]

supreme wiki link seems broken.

Some information lies there:

viewtopic.php?f=48&t=16453