The instructions above apply to the official Blizzard client. If you are playing on a custom private server that goes by that specific name, the option is likely located in the same area (Menu > System > Advanced), but some custom servers hard-code these features to always be on. In that case, you would need to check the specific forum or Discord for that server to see if a console command (like /console floatingCombatText 0 ) is required.
If commands don't stick or you want more control, use these tools to manage "hidden" interface settings: AdvancedInterfaceOptions how to turn off damage numbers in wow exclusive
Scroll down to section (separate from Scrolling Combat Text). The instructions above apply to the official Blizzard client