Cant remove /var, in relocating /var to a symbolic link

[jaymax2U]

I am attempting to relocate /var to avoid files system full issues.
Using an -
mkdir /usr/var
cd /var
tar cf - . | (cd /usr/var; tar xf - )
cd /
rm -rf /var
ln -s /usr/var /var
approach

at the
rm -rf /var step, the following was received
rm: /var/empty: Operation not permitted
rm: /var/named/dev: Device busy
rm: /var/named: Directory not empty
rm: /var: Device busy

Te contents of /var at this site was
ls /var
./ ../ empty/ named/
and
ls /var/empty/
./ ../

ls -l /var/empty/
total 4
dr-xr-xr-x 2 root wheel 512 Nov 3 2005 ./
drwxr-xr-x 4 root wheel 512 Oct 6 14:02 ../

Can't change permissons either
chmod 755 /var/empty/
chmod: /var/empty/: Operation not permitted

while
ls /var/named/
./ ../ dev/
ls -l /var/named/
total 5
drwxr-xr-x 3 root wheel 512 Oct 4 19:46 ./
drwxr-xr-x 5 root wheel 512 Oct 6 14:16 ../
dr-xr-xr-x 4 root wheel 512 Jan 1 2002 dev/

ls -l /var/named/dev
total 0
Could chmod755 but still cant remove, dev, dir empty but => Device busy

How can I remove these two directories so that I can create a link from /usr/var to /var