To remove the old version of Julia, delete the old directory with the following command:
rm -r julia-1.6.0
To remove the symbolic link from the old version of Julia, go to the bin folder with the following command:
cd bin
Then, delete the symbolic link with the following command:
rm julia
After doing this, you can download the new version of Julia normally:
wget https://julialang-s3.julialang.org/bin/linux/aarch64/1.6/julia-1.6.1-linux-aarch64.tar.gz
tar -xvzf julia-1.6.1-linux-aarch64.tar.gz
rm julia-1.6.1-linux-aarch64.tar.gz
And finally, create the symbolic link for the new version:
ln -s "$HOME"/julia-1.6.1/bin/julia "$HOME"/bin