I no longer have Sooloos, so can't verify, but if I remember correctly, you do so by swiping from right to left (like deleting an email from a list in iOS).

Living room: 818v3, Audio Research D150, Maggie 1.6
A/V room: 861v8, DSP7200SE L/R/C, 4x DSP320 surrounds, ID41 + Roon, UHD722, Prime+PS