With ABS, sensors mounted at each wheel monitor the speed at which the wheels are turning. If one is turning slower than the others during braking, that indicates it is locking up, which could cause skidding and loss of steering control. ABS is supposed to intervene by rapidly "pumping" the brakes at the wheel that is locking up, allowing it to spin so that the driver retains braking and steering control.
Unplug the wiring harness from the window motor. You will have to press down on the clip that holds the wiring harness into place and pull the harness out. These can be hard to press and sometimes it is best if you can get a screwdriver on it to press it in. Unbolt the harness andor motor from the door's interior. Any bolts holding the harness and motor will have to be removed.
These can often be difficult to bolts to remove. You may need to use a ratchet with a long extension to provide the necessary angle to access and turn the bolts. Pull the motor and harness out as one assembly. Once you have the assembly removed, you can separate the two pieces and replace the one that is malfunctioning. Re-install the motorregulator assembly. Once you have replaced the malfunctioning part, whether it was the motor or the regulator, it is time to slide the assembly back into the door's interior and bolt it back into it's original position.
ABS stands for antilock braking system, and if the ABS warning light is illuminated in your car's gauge cluster, that means the antilock system has been deactivated because of a malfunction. Your car's regular brakes should work fine, but the antilock feature that prevents wheels from locking up during braking will not work. In addition, if your vehicle has stability control and traction control, those will be disabled as well because those systems rely on the same wheel-speed sensors as the antilock system.