MacOS: Rationalising Fonts — Cannot disable fonts
The fonts you are trying to disable are used by the System and hence are protected. You could still try to delete those fonts but I would not advise that.

I suggest you start over and try deleting one font at a time. if the font you try to disable is dimmed out then it is a system font. Use the disable button in font book to diable the fonts. This is shown below.