How do I uninstall the Pantone Connect Extension?

This depends on how the Pantone Connect Extension was initially installed.

If this was installed via the Adobe Exchange Marketplace, this can be uninstalled via the Adobe® Creative Cloud® Desktop app.
If installed using a 3rd party Extension Manager such as the Anastasiy Extension Manager, you will need to use this to uninstall. This can be accessed at https://install.anastasiy.com/