Install oh my zsh for the root user and for all users.txt

1. sudo sh -c "$(wget https://raw.github.com/robbyrussell/oh-my-zsh/master/tools/install.sh -O -)"
2. sudo ln -s $HOME/.zshrc   /root/.zshrc

If you have .zshrc file first remove these, and then do the system link command required to create it again
sudo ln -s $HOME/.zshrc   /root/.zshrc

3. sudo ln -s $HOME/.oh-my-zsh   /root/.oh-my-zsh
4. sudo chmod 744 /root/.zshrc

5. chsh -s $(which zsh) $(whoami)

6. add "typeset -g POWERLEVEL9K_INSTANT_PROMPT=quiet" to ~/.zshrc
7. sudo chown -R root:root /usr/local/share/zsh/site-functions
8. sudo chmod -R 755 /usr/local/share/zsh/site-functions

Other method (Recommended)

1. sudo sh -c "$(wget https://raw.githubusercontent.com/robbyrussell/oh-my-zsh/master/tools/install.sh -O -)"
2. git clone --depth=1 https://github.com/romkatv/powerlevel10k.git ${ZSH_CUSTOM:-$HOME/.oh-my-zsh/custom}/themes/powerlevel10k

3. cd .oh-my-zsh/themes
4. sudo cp -rf custom /root/.oh-my-zsh/themes
5. sudo cp -rf .oh-my-zsh/custom/themes/powerlevel10k /root/.oh-my-zsh/custom/themes/
6. sudo su
7. nano .zshrc and change your zsh theme with ZSH_THEME="powerlevel10k/powerlevel10k"
8. source .zshrc