Function  41h   Delete A File From A Specified Subdirectory  (UNLINK) 
entry   AH      41h 
	DS:DX   pointer to ASCIIZ filespec to delete 
return  CF      0       successful 
		1       error 
		AX      error code if any  (2, 5) 
note 1) This function will not work on a file marked read-only 
     2) Wildcards are not accepted 
     3)	DOS does not erase the file's data; it merely becomes inaccessible
	because the FAT chain for the file is cleared.
     4) Deleting a file which is currently open may lead to filesystem
	corruption.  Unless SHARE is loaded, DOS does not close the handles
	referencing the deleted file, thus allowing writes to a nonexistant file.
     5) Under DR DOS and DR Multiuser DOS, this function will fail if the file
	is currently open

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