Incompatible node version - what to do?

I’ve gotten myself into a pickle.

I tried to update to v3.5 Ghost so that I could then update to v4. Unfortunately, somewhere along the way I updated node. And now the node version is incompatible with my ghost version.

I have found instructions for setting up nvm, but this is all feeling a bit overwhelming. Am I just better off uninstalling node completely and installing the correct node version? Or is there another suggested path for noobs like myself using the self-hosted version.