Can anyone let me know how can I redirect 404 page to the homepage? I want to redirect any not found page to home page.
You can use .htaccess with something along these lines.
ErrorDocument 404 http://generalautostore.com/
In your magento .htaccess look for 'ErrorDocument 404 /pub/errors/404.php' and replace the '/pub/errors/404.php' bit with your url or simply
/ for site root.
More info here: http://www.htaccessbasics.com/404-custom-error-page/
If still in trouble, maybe this will help: 404 page url in magento 2