turn off negative with ignition on

Does anyone know how to turn off a negative wire I guess that's how I would put it while the ignition is turned on. Right now I have my alarm wired so when i unlock/lock my car and the parking lights are set to a timer triggered by the unlock/lock wires . And I pretty much want the negative wire to the timer disconnected once I turn the ignition on so I'm not driving around with my parking lights on while there is still time on the timer. And then once I turn off the ignition the ground for the timer is grounded again so that it works normal. Thanks in advanceNever stop learning

Use a 5 pin Bosch/tycho cube automotive relay. Cut NEG wire. One side to 30, other to 87a. Ground to 85 and ignition to 86.