src/vs/platform/configuration/common/configurationRegistry.ts/ConfigurationRegistry/deregisterDefaultConfigurations
class ConfigurationRegistry:	public deregisterDefaultConfigurations(defaultConfigurations: IStringDictionary<any>[]): void {
		const properties: string[] = [];
		for (const defaultConfiguration of defaultConfigurations) {
			for (const key in defaultConfiguration) {
				properties.push(key);
				delete this.defaultValues[key];
				if (OVERRIDE_PROPERTY_PATTERN.test(key)) {
					delete this.configurationProperties[key];
					delete this.defaultLanguageConfigurationOverridesNode.properties![key];
				} else {
					const property = this.configurationProperties[key];
					if (property) {
						this.updatePropertyDefaultValue(key, property);
						this.updateSchema(key, property);
					}
				}
			}
		}

		this.updateOverridePropertyPatternKey();
		this._onDidSchemaChange.fire();
		this._onDidUpdateConfiguration.fire(properties);
	}