It might be easier to help if you give an example of a preset that you mean.
There's a few places that it could maybe originate from. You should check the Adsynth oscillator editor (go to edit instrument -> adsynth -> show voice parameters -> change) and change h.rnd to "none" and maybe put the rnd slider closer to 0. Or you can change the LFO depth knobs in adsynth global parameters window to 0.
You can find the effects like reverb in the instrument edit window if you click effects or on the first window in either system effects or insertion effects. Or you can turn down R.dt in the amplitude envelope in the adsynth global parameters window if that's causing the "reverb".