Help I accidently deleted High Fidelity Preset in Ai under Image trace

Did you delete it from your custom vectorize preferences file?

In that case when you move that file out of the preferences folder, the original prefs should be rebuilt. 

Afterwards you need to set up a new custom preset, then you get a new vectorize presets file and then you can copy your other presets into it in a text editor.

rebuilding the presets via the method Ton described should be less work in this case, but just in case someone needs this ...

But you can recreate and save a new one based on these settings:

In Illustrator, unfortunately, there's no built-in way to recover deleted High Fidelity image tracing presets after trying the trash, resetting preferences, and undo history.