For this you need to create one .php file with phpinfo() function which show you all the information at your browser.
Please create the file with the name phpinfo.php or you can create with any name.
Open the file and write the below code in the file
<?php
// Show all current running php information
phpinfo();
?>
and then save this file and upload it at your root directory.
After uploading you can open it at your browser as like
http://www.YourDomainName.com/Filename.php
Example : http://www.abc.com/phpinfo.php
It will show you all the running information of php
Note : You can upload this .php file at the root directory and its not matter that which hosting control panel you are using.
For cPanel : Under public_html (Generally its a root directory)
For Plesk Panel : Under httpdocs (Generally its a root directory)
For Website Panel : Under wwwroot (Generally its a root directory)
For Helm Panel : Under wwwroot (Generally its a root directory)