add a function to delete custom keys and values on the payload

payload/builder.go

@@ -232,6 +232,15 @@ func (p *Payload) Custom(key string, val interface{}) *Payload {
 	return p
 }
 
+// UnsetCustom unsets a custom key and value on the payload.
+// This will delete custom key/value data from the notification payload at root level.
+//
+//	{"aps":{}}
+func (p *Payload) UnsetCustom(key string) *Payload {
+	delete(p.content, key)
+	return p
+}
+
 // Alert dictionary
 
 // AlertTitle sets the aps alert title on the payload.

payload/builder_test.go

@@ -81,6 +81,12 @@ func TestCustomMap(t *testing.T) {
 	assert.Equal(t, `{"aps":{},"key":{"map":1}}`, string(b))
 }
 
+func TestUnsetCustom(t *testing.T) {
+	payload := NewPayload().Custom("key", "val").UnsetCustom("key")
+	b, _ := json.Marshal(payload)
+	assert.Equal(t, `{"aps":{}}`, string(b))
+}
+
 func TestAlertTitle(t *testing.T) {
 	payload := NewPayload().AlertTitle("hello")
 	b, _ := json.Marshal(payload)