These are the tables affected when you run program RSWWWIDE to delete workitems.
SWZAIRET
SWZAIENTRY
SWZAI
SWW_WI2OBJ
SWW_CONTOB
SWW_CONT
SWWWIRET
SWWWIHEAD
SWWWIDEADL
SWWLOGPARA
SWWLOGHIST
SWWEI
SWWCNTPADD
SWWCNTP0
SWP_NODEWI
SWP_HEADER
SWPSTEPLOG
SWPNODELOG
SWPNODE
SWPCMPCONT
SWFGPROLEINST
You can use table SWWWIHEAD to track the number of entries deleted and space changes. Because this is the header table.
How ever you can use program RSWWWIDE log to find out from which table the entries got deleted and how much space has been gained.