Is there a key command to disable playback start offset?
Are you referring to Note Performer delay? That is unavoidable, since it has to work out all the articulations and expression and so on. That is documented in their manual. But I am not sure what you mean.
No, I’m referring to a Dorico named parameter called Playback Start Offset . It is applied to individual notes so they may start at the time offset as recorded, not as notated.
I have no issue with Noteperformer delay, been fine with that for years.
There’s no key command to clear only that single parameter. You can use Play > Reset Playback Overrides, but that will also remove the end offset and velocity values.