If you were to re-run the sage installer, it could overwrite that file, though there’s a prompt to ask first before it gets overwritten. I would guess few people re-run the installer once they’ve picked a framework, unless they’re changing frameworks or want to reset the framework files. If you’re using git for the project (which I really hope you are!) there’s little risk here.
If you really, really want to avoid editing that file, you can go through resource/styles/main.scss by changing
/** Import everything from autoload */
@import "./autoload/**/*";
If you didn’t install font awesome, you can remove that line. If you did, change to this:
/** Manually import autoload */
@import "./autoload/fontawesome";
Then above the npm dependencies block add the specific components for bootstrap like such:
@import "~bootstrap/scss/functions";
@import "~bootstrap/scss/variables";
@import "~bootstrap/scss/mixins";
@import "~bootstrap/scss/root";
//...etc
/**
* Import npm dependencies
*
* Prefix your imports with `~` to grab from node_modules/
* @see https://github.com/webpack-contrib/sass-loader#imports
*/
// @import "~some-node-module";
/** Import theme styles */
@import "common/global";
@import "components/buttons";