How can you delete a specific part of a string in PHP?

To delete a specific part of a string in PHP, you can use the `substr_replace()` function. This function allows you to replace a portion of a string with another string or simply remove it by passing an empty string. You need to specify the start position of the substring you want to delete and the length of characters to remove.

$string = "Hello, World!";
$start = 7; // start position of the substring to delete
$length = 7; // number of characters to delete
$newString = substr_replace($string, "", $start, $length);
echo $newString; // Output: Hello!