<?php
$re = '/Grup [A-Z]/';
$str = 'Grup I: Kroasia vs Islandia';
$subst = '';
$result = preg_replace($re, $subst, $str);
echo "The result of the substitution is ".$result;
The result of the substitution is : Kroasia vs Islandia
Output for 8.3.5
Warning: PHP Startup: Unable to load dynamic library 'sodium.so' (tried: /usr/lib/php/8.3.5/modules/sodium.so (libsodium.so.23: cannot open shared object file: No such file or directory), /usr/lib/php/8.3.5/modules/sodium.so.so (/usr/lib/php/8.3.5/modules/sodium.so.so: cannot open shared object file: No such file or directory)) in Unknown on line 0
The result of the substitution is : Kroasia vs Islandia