Unable to remove index.php on Google Cloud server.

First, make sure that the web server has mod_rewrite enabled.

If it is enabled then you need to check if .htaccess is being handled. You can easily do that by putting useless text in the first line of the file. Any word will do as long as it is not a valid .htaccess command. Direct a web browser to the site. If the site shows then .htaccess is not being read. What you should see is 500 Internal Server Error message. Remove the change you made to .htaccess before you do more troubleshooting.

Let us know what happens.