Update: December 2020 - I have updated the answer because previous one was not relevant.
Follow below steps to update your node version.
1. Install nvm For this run below command in your terminal
curl -o- https://raw.githubusercontent.com/nvm-sh/nvm/v0.37.2/install.sh | bash
2. Install specific node version using nvm
For this run
Replace 12.14.1
with your node version
nvm install 12.14.1
Note: If you are getting error of NVM not recognised then run below command and then run above again
source ~/.nvm/nvm.sh
3. Make the installed version default
Note: Replace 12.14.1 with your installed version.
nvm alias default 12.14.1
4. Check node version
node -v
And that's it. Cheers!