Get a list of what's left in the library:
WRKOBJ OBJ(TESTDTA/*ALL)
Look in your job log to see why the file cannot be deleted:
DSPJOBLOG
Press F10 to see lower level messages, and page up to see more details.
Use Display Database Relations (DSPDBR) command to see if there are logical files (logical views) over the physical file (table):
DSPDBR TESTDTA/F470371
This will list logical files that may need to be deleted.
Post back!
Barry