Can I make a slowed remix without adding reverb?

Yes. Set the Reverb knob to 0% and adjust only Speed for a clean slowed remix. Reverb works well for rap remixes, phonk songs slowed down remixes usually don't have reverb added. Speed and Pitch are separate controls, so you can slow the rhythm while keeping the original musical tuning, or transpose the pitch deliberately by semitones.

Setting Reverb to 0% disables the reverb added by Neural Analog. It does not remove room reverb that is already part of the source audio; use the Remove Reverb tool for that.