To use the below features, click the Gear icon in lounge, then click on Advance Settings, then scroll down to the Custom CSS box where you can then add in what ever you want to do:  (Also, you can use the Sync settings so that this is in effect for all your devices on lounge)

The below would prevent any message from IzzyCreamcheese from being seen on your lounge:

#chat .msg[data-name="IzzyCreamcheese"] {
    display: none;
}

The below would prevent any message from Squishy[MR] from being seen on your lounge:

#chat .msg[data-name="Squishy[MR]"] {
    display: none;
}

In fact, you can change the styling for any user, any channel, any specific thing actually in all of lounge.  Feel free play around with stuff, colors, animations, bold, invisible, whatever!