Unfortunately, you can't unpack a mod. That's not how the modkit works. You'll just have to make an alternate version of Better Fields that meets your requirements.

Also, what exactly is the problem you're having? I might be able to tell you how to fix it. Better Fields is a pretty simple mod.

CC already changes how you can place fields§pastures/orchards, adds denser orchards and add the option to have labourers pick up the harvest instead of the farmers. You don't really need Better Fields with it.