While DELETE FILE will only do one file at a time, it's relatively simple to cycle through all the files found that match a given filemask / skeleton. I'm sure you could write this for yourself, but it's always easier to use existing code then think it through again!
This function returns 0 if it successfully deletes all files that match pcMask. If any files can't be deleted, the number of files that couldn't be deleted is returned.
This function should never throw an error, even if some files are in use.