First you will have to read the data using SCB_UartGetChar() or SCB_UartGetByte().
Then you may clear the interrupt causes by SCB_ClearRxInterruptSource(). The parameter is a bit mask which interrupt to clear, 0xff clears all, SCB_GetRxInterruptSource() gets all currently due interrupts SCB_GetRxInterruptSourceMasked() gets all enabled and due interrupts..
Ahh, thanks a bunch! Didn't think about checking the header file for that function.