theme_functions.php

//delete user
function delete_my_user_account($request) {
    if ( is_user_logged_in() ) {
        // Can't delete admin accounts
        if ( current_user_can( 'manage_options' ) ) {
            wp_send_json( array(
                'status' => 'fail',
                'title' => __( 'Error!', 'wp-delete-user-accounts' ),
                'message' => __( 'Administrators cannot delete their own accounts.', 'wp-delete-user-accounts' )
            ) );
        }

        // Get the current user data
        $user_id = get_current_user_id();

        // Get user meta data
        $meta = get_user_meta( $user_id );

        // Delete user's meta data
        foreach ( $meta as $key => $val ) {
            delete_user_meta( $user_id, $key );
        }


        // User Logout
        wp_logout();

        if ( ! function_exists( 'wp_delete_user' ) ) {
            require_once(ABSPATH.'wp-admin/includes/user.php' );
        }

        // Delete the user's account
        $deleted = wp_delete_user( $user_id );


        if ( $deleted ) {

            // Success
            return array(
                'status' => 'success',
                'title' => __( 'Success!', 'wp-delete-user-accounts' ),
                'message' => __( 'Your account was successfully deleted. Fair well.', 'wp-delete-user-accounts' )
            ) ;

        } else {

            return  array(
                'status' => 'fail',
                'title' => __( 'Error!', 'wp-delete-user-accounts' ),
                'message' => __( 'Request failed.', 'wp-delete-user-accounts' )
            ) ;
        }
    }
}


add_action('rest_api_init', function () {
  register_rest_route( 'remove_user/v1', 'user/me',array(
                'methods'  => 'DELETE',
                'callback' => 'delete_my_user_account'
      ));
});