I want to have only the FPS and the time to be displayed. On my screenshot you can see a setting with 16.7ms. I have no idea what this is, How can i remove this and keep only the FPS and the time?
There should be a config file in ~/.config/MangoHud (you can check more details in the GitHub page https://github.com/flightlessmango/MangoHud#hud-configuration).
By adding frametime=0 to the config file, you should be able to remove the frametime measurement from the FPS display.