You do not remove anything necessary if you completely remove the two lines. Your PATH is set up somewhere else. These two lines just overwrite the content of the already existing PATH variable. Consider the command you issued:
# echo "PATH=$PATH: /usr/lib/tcl/" >> ~/.bashrc
this told to echo the value of the PATH variable. You see this value has been expanded by the shell before actually writing the line in .bashrc. This means the PATH was already set before. Just remove the two lines, save and quit. Then close the root's session and start a new one (that is just open another terminal and do su -
and check if it is correct.