Can I disable the output without turning the 33120A off?

The 33120A does not have a simple ON/OFF switch for the output. One possible method of producing zero output is to output 0 Volts dc. The desired instrument state may be stored and then recalled when desired.To set the 33120A to 0 Vdc from the front panel, hold down the "Offset" key for about two seconds. The dc offset voltage will then be output, which may be adjusted to 0 V. From the remote interface, issuing the SCPI command APPLy:DC DEFault, DEFault, 0 has the same effect.For more information on generating a dc voltage, see How do I generate a dc voltage output from the Keysight 33120A?