When I'm building firmware I'm cpnfiguring it via make menuconfig.
I've built firmware with some packages, then I decided to rebuild it without some of them.
If I'm disabling some package that have dependecies, does dependencies deselects automaticaly?
In my experience, they do not deselect under
Thats correct, you need to do a diffconfig see: https://openwrt.org/docs/guide-developer/build-system/use-buildsystem
Than remove the packages/deps you don't need anymore and use it as a fresh .config.