Remove the abs fuses and unhook the plugs from the abs pump. Also look for a non abs conversion for sale and drop the 19lb boat anchor from your left front.

I've had the same thing happen and yes its very scary. The ABS is horrible and poorly engineered in these cars so your best bet is to pull the fuse on the battery cable fuse block and or completely remove it cause its not worth trying to fix

Just the main fuse on the battery fuse block will disable the system. to shut the light down you need to unplug the abs module mounted in the trunk (drivers side by the antenna motor, under the side liner). this will take the ABS out of play.

To do a proper full on abs delete you'll need front hard lines from a non abs eclipse or lower trim level galant. I used a brake proportioning valve from a 3000gt but others will also work. Ideally use one from a four wheel disk car to maintain the front rear brake bias.