void pcre2_match_data_free(pcre2_match_data *match_data);
If match_data is NULL, this function does nothing. Otherwise, match_data must point to a match data block, which this function frees, using the memory freeing function from the general context or compiled pattern with which it was created, or free() if that was not set.
If the PCRE2_COPY_MATCHED_SUBJECT was used for a successful match using this match data block, the copy of the subject that was remembered with the block is also freed.
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.