How to change /index.php/ to no index.php :- The default startup condition now for sh404, after you enable it, is to work without an htaccess file. You can leave it like this if you like (we do, on this site). It has no effect on search engines for example - we have around 50 #1 or #2 global search results here, on this website, so obviously the search potential is unaffected. The URL will look like this:
www.a3webtech.com/index.php/install-sh404.html

You'll see it has an extra level in the middle that looks out of place and could be removed. As stated, you can leave it like this - and we do, since we like the fact it works entirely within the CMS and doesn't use an htaccess file. It's greener :)

Many people will want to fix it though. That means you must use an htaccess file. In the past this was the default, but so many people had problems just getting the plugin to work the developer got tired of it and changed the default, so that it always works - but it has an extra level within the URL.

You will now be using the Apache server rewrite function (the server rewrites the URL to a better format). This is enabled within the server local configuration file, called the htaccess file. First we will check to see that the built-in Joomla SEF / htaccess solution works. If it doesn't, there won't be much point going any further, sh404SEF certainly won't.

First switch off sh404 if you had it enabled. We now want to check the core SEF solution works, as a first job.

1. In the standard Joomla htaccess file, you'll see that the core SEF rewrite section - 'Begin - Joomla! core SEF Section' - at around lines 66 to 78, is uncommented and therefore live and operational. That htaccess file should be in your server webroot, with all the other Joomla files and folders.

2. Go to your backend admin >> text menus at top of page >> Site >> Global Configuration >> SEO tab at far right >> check 'Yes' for Search Engine Friendly URLs.


3. Check the livesite (your working website). Now, it should have different URLs showing. They will be shorter and definitely better than the initial 'raw' URLs. But they can be improved.

4. Now go to your htaccess file again. Comment-out the Joomla Core SEF Section at lines 66 - 78.

5. Uncomment the 'Begin - 3rd Party SEF Section' at lines 82 to 92. Actually you don't uncomment all of them - just do the lines of working script of course, which are from 86 to 90. Those are the lines with a single hash (#), which you remove to set that line live. The server now reads it.

6. FTP the changed htaccess file up to the server and overwrite the original.

7. Go to your admin backend, to the sh404 configuration.
In the admin backend >> text menu at top >> Components >> sh404SEF >> sh404SEF Configuration (the top left blue button) >> Main tab >> Enabled = Yes.
Then go to the Advanced tab >> Advanced Component Configuration >> Rewriting mode >> change spin box selection, to 'with htaccess (mod_rewrite)'.

Thanks : http://www.a3webtech.com/index.php/install-sh404.html