How to disable UART Tx

I'd like to disable UART Tx when CC2530 is going to 'PWRMGR_CONSERVE' state.
How can I disable UART Tx?

Detail:

- I use CC2530ZDK.

- I use osal_pwrmgr_task_state(My_App_TaskID, PWRMGR_CONSERVE); 
   see http://e2e.ti.com/support/low_power_rf/f/158/t/153290.aspx#555159 

- Before going to conserve state, I use 'HalUARTSuspend();'

- Even when ED is the conserve state, UART Tx (P0_3 pin) is high(=3.3V out).
  And in my system, it causes the electric leak.

- I found the function 'HalUARTClose()' in HAL Drivers API (SWRA193).
  But it isn't implemented. (Z-stack 2.5.0, IAR workbench 8.10.3) 

- I study 'CC253x User's Guide' (SWRU191B) and 'Using UART in CC253xFx' (DN112).
  And I found the correspond registers; P0SEL, P0DIR, P0, P0INP.

- I added the code to change the registers when state change. But it did't work.
 UART Tx remained to be High. It was opposite of my intention.

Here is the code:

// Go into the conserve state:

      HalUARTSuspend();
      P0SEL &= ~0x0c;
      P0DIR &= ~0x08;
      P0 &= ~0x0c;
      P0INP |= 0x0c;
      osal_pwrmgr_task_state(TaskID, PWRMGR_CONSERVE); 

      break;

 // When back to HOLD state:

      osal_pwrmgr_task_state(RemoteCamClient_TaskID, PWRMGR_HOLD);
      P0SEL |= 0x0c;
      P0DIR |= 0x08;
      P0INP &= ~0x0c;
      HalUARTResume();

      break;

Question

1. How can I disable UART Tx ?

2. If I can, I'd like to disable UART Rx, too. How ?

3. If my scenario above is not well, I'd like to use 'HalUARTClose()' function.
  Please teach me the implement of the function.

Regards.