How to delete or replace an already created symbolic link?

ln has -f switch that 'forces' a symlink to be created whether it exists or not.

sudo ln -sf /home/vinaychalluru/ns-allinone-2.34/ns-2.34/ns /usr/bin/ns

sudo rm -r /usr/bin/ns

sudo ln -s /home/vinaychalluru/ns-allinone-2.34/ns-2.34/ns /usr/bin/ns

I tried ln -sf while replacing but it didn't work for me, but doing ln -sfn directory link_name as root worked.