How do I remove old files?

[pokkur]

number of files will increase every time.

main.3b49b520.css
main.480223cd.css
main.a270c389.css
main.f475a73e.css

I just need only newest one file.
Please tell me if anybody know.

[EdMakes]

var del = require("del");
//delete the old file. be cautious that the glob pattern does't match a file you want to keep.
del("main.*.cs");
// run the code to generate the new file

[pokkur]

Thank you @cognitivefusion ,
I knew that. now I do that.

// current
const del = require('del');
gulp.task('css:del', (cb) => {
    return del(`${config.scss.dest}/**/*.css`, {force: true}, cb);
});

But practically, there are a lot of resources(css, js).
It mean, auto remove only useless files.