Your Valve Controller's Access Point is only used during set up. Should you want to disable it from showing up in your available Wi-Fi connections after set up has been completed, please press and hold the grey button on your Valve Controller until you hear 3 beeps. Similarly, the Access Point can be re-abled by pressing and holding the grey button until you hear 3 beeps.
After this, please check your available Wi-Fi connections to confirm success. You can also refer to Valve Controller LED behavior to verify if Access Point has been successfully disabled.