In order to manipulate notes according to their SATB voice, first, each voice must be on it’s own midi channel. Once that is so, this can be accomplished in the Score Editor by using Polyphonic Staff Mode.
Now, in the Score Editor each SATB line’s notes can be selected with shift+double-click, and you can mute the lines you want to mute using the Edit>Mute/Unmute Objects key command, or with a Logical Editor Preset.
By the way, the Bach chorales, and much of JS Bach’s opus are available online thanks to the hard work of midi musicians starting right when midi first was implemented. Do a search for bach chorales midi