Using pin 6 as GPIO in SPI functionality

How do I find where else in the program pin 6 is being used and disable its other functionalities in the BLE_UART example? 

I am trying to read data from a sensor via SPI communication and then transfer the data the SPI reads via bluetooth to the Nordic mobile app. I am starting with the ble_uart example and add SPI instance and functions. IDE is Embedded Studio, SDK 15.2, and the chip I am programming is a custom made PCB device (nrf52832). Program builds and flashes alright and the chip advertises and sends random data too. 

But I cannot seem to use pin # 6 on my device as a GPIO. It's HIGH (3.3V) even though I am clearing it in the program. This is important because pin 6 is a chip select for my ADC (ADS1220) so I need to fix it to LOW and make sure my pins are being defined correctly as SPI pins and not being used in other things.

I previously had the same problem when I was working with the SPI master example on my chip. I fixed it by redefining the UART_TX pin from 6 to pin # 5 in the sdk_config.h file so that I could use pin 6 as a GPIO only and its uart functionality was disabled. This solved the issue. Now that I start with the ble_uart example and add the SPI code and try to work with it I see that my pin 6 does not go low when I clear it. (Same problem I was having before in the spi master example but now  I cannot find any other use of pin 6 in the sdk_config.h file of the ble_uart example.