Deleting a setting in Viper (any config type)

config-del.yaml

bobjects:
  limit: 100
foo:
  blatz: quux

config.yaml

bobjects:
  limit: 100
foo:
  bar: baz
  blatz: quux

viper-test.go

package main

import (
	"log"
	"os"
	"path/filepath"

	"github.com/spf13/viper"
)

func main() {
	cfgType := "hcl"
	if len(os.Args) > 1 {
		cfgType = os.Args[1]
	}

	mkCfgFileName := func(base string) string {
		return filepath.Join(os.TempDir(), base+"."+cfgType)
	}

	viper.Set("foo.bar", "baz")
	viper.Set("foo.blatz", "quux")
	viper.Set("bobjects.limit", 100)
	if err := writeConfig(mkCfgFileName("config")); err != nil {
		bail(err)
	}

	viper.Set("foo.bar", nil)
	if err := writeConfig(mkCfgFileName("config-del")); err != nil {
		bail(err)
	}
}

func writeConfig(filename string) error {
	viper.SetConfigFile(filename)
	return viper.WriteConfig()
}

func bail(err error) {
	log.SetFlags(0)
	log.SetPrefix("error: ")
	log.Fatalln(err)
}