void pcre2_substring_list_free(PCRE2_SPTR *list);
This is a convenience function for freeing the store obtained by a previous call to pcre2substring_list_get(). Its only argument is a pointer to the list of string pointers. If the argument is NULL, the function returns immediately, without doing anything.
There is a complete description of the PCRE2 native API in the pcre2api page and a description of the POSIX API in the pcre2posix page.