public void removeItem(final String key) {
        this.apolloOpenApiClient.removeItem(
                apolloConfig.getAppId(),
                apolloConfig.getEnv(),
                apolloConfig.getClusterName(),
                apolloConfig.getNamespace(),
                key,
                DEFAULT_USER
        );
    }
remove item from namespace.
@param key item key
shenyu-registry/shenyu-registry-apollo/src/main/java/org/apache/shenyu/registry/apollo/ApolloClient.java