yagarto-arm-elf-ar.exe

I am using yagarto last version.(4.4.2)
i want to delete the syscalls.o from the libc.a file using the line 
below.

--------------------------------------------------------------
arm-elf-ar.exe -d "C:\arm\yagarto43\arm-elf\lib\libc.a  syscall.o
-----------------------------------------------------------------
but syscalls.o can not be deleted! (i can see it in .map file).

do you have another solution?

Regards

kamil