No, the file I tried to remove is not the booting kernel. 

At 04:17 PM 12/26/96 -0800, David Haube wrote:
>If it's the kernel is the one you booted from, you can't delete it, the
>file is still open.  To replace the kernel, rename netbsd to somethinge
>else, put your new kernel in as /netbsd, then reboot.  When you
>come back you can erase the old kernel.
>
>Also, it's good to keep the old kernel around in case the new kernel
>has a problem, you can boot the old kernel from the boot prompt.
>
>On Thu, 26 Dec 1996, Yi-Chun Chu wrote:
>
>> Hi:
>> 
>> I compiled a new kernel and put it in the root. When I tried to delete it,
>> I got error messages.
>> 
>> /> ls -l netbsd
>> -r-xr-xr-x  1 root  wheel  1064524 Dec 20 12:59 netbsd
>> /> rm netbsd
>> remove netbsd? y
>> rm: netbsd: Operation not permitted
>> /> chmod +w netbsd
>> chmod: netbsd: Operation not permitted
>> /> 
>> 
>> I even tried to delete it in the single user mode, but it is still not
>> working. Anyone can help? Thank you in advanced.
>> --ycchu
>> 
>
>