Renaming Joomla Installation Directory is very easy just rename the directory/folder i.e. “test” to “testing” and enjoy! Its work great for default Joomla installation.
Image Source: resources.joomla.org/images/infographics/The_Joomla_Resources_Directory_Team_Version_2.jpg
But if you have any their party extension installed that need path you need to update them. Also don’t forget to check your .htaccess and local php.ini files If you have made any special changes to this.