Hi Slarok,

You can always mute the strings with your right hand when lifting off with your left hand. But usually you're only lifting your fretting hand when switching chords, and usually when you're switching chords, you'll be doing it fast enough so that the lift off sound isn't audible during a chord progression.

It's okay to lift off slowly when practicing new chord switches, to build muscle memory but I wouldn't worry about it too much when you're playing a song at full speed, because it's usually inaudible.