Safe to remove /usr/local/bin/node?
Solution 1:
you are installing node from binaries which is self installation (not using ubuntu software center).
When you do self installation of node usually you create a symbolic link to /usr/bin or /usr/local/bin to put in the path for everyone system-wide.
If you installed new version of node all you have to do is to remove the symlink of the old one and place the new one instead.
ln -s /path/where/node/installed/bin/node /usr/bin/node
Remove of course the one in /usr/local/bin or /usr/bin before.
Solution 2:
Yes. It is safe to remove /usr/local/bin/node
folder but you have to remove or edit Nodejs from the PATH in ~/.bashrc.