How do I disable the electronic hatch. It opens and then closes immediately

Hello, I don't recommend it, especially if children may need to open the hatch. The hatch can get very heavy without the motor, and, in some models, the motor is energized to act as a brake when the hatch not moving. If the Flex does not have the hatch brake feature, the weight of the hatch will still be a chore for anyone to lift, especially if the struts are going bad. Ford has a software patch for the issue available, and you will probably have to pay for the time spent programming, or nothing at all. If you are determined to try removing power, just pull the fuse for the rear lift-gate assembly.