Cannot uninstall or update ghost-cli locally due to previous version

[matenauta]

It seems that you need to remove conflicting versions of Ghost CLI.

See this solution to similar issue:

Can't install because node version (loop)

This is an environment issue, usually signifying that might have multiple versions of the CLI installed. You can use whereis ghost to check. For example, my locally installed CLI version is 1.26.0: $ ghost -v | grep version: Ghost-CLI version: 1.26.0