PC - The Quadcast's mic monitoring can be disabled by going to Control Panel>Sound>Recording. Select the HyperX microphone and click Properties. Select the Listen tab and then disable "Listen to this device."

The Quadcast S can be adjusted through Ngenuity under the Mic monitoring feature

MAC - Open the Audio MIDI setup, select HyperX Quadcast and check/uncheck the "thru" checkbox accordingly

PS4 - No. Unfortunately, there is no option to disable the Quadcast's mic monitoring feature on PS4. However, you can bypass the mic monitoring feature by connecting a headset to the PS4 controller. To proceed, see steps below:

First, disconnect the Quadcast from the PS4 and connect your headset to the PS4 controller via the 3.5mm headset jack.
Next, navigate to the PS4 Settings (pictured below) and select Devices then Audio Devices.

Remove the check from "Switch Output Devices Automatically" and then connect the HyperX Quadcast microphone.