What is the procedure to remove the ECU in a 1993 Ford Festiva?

Get a 10mm wrench (ratchet wrench is ideal). Open the drivers door and either lay on your back or side looking up under the dash / steering column area. You'll see the ECU sitting there. You need to find the two 10 mils and remove them. There is also a tab that locks the ECU to the body of the car (or framework of the dash). I think you have to push it up into the dash more to get it off the tab lock. Then wiggle it out. I can't remember if the plugs are on the top or bottom but you'll figure out what to do. Either unplug them first and then remove it or you need to remove it an then unplug. It's been a while. Hope this helps and ask any further questions :)

Additionally, most of us don't lock it back or re-install the two 10 mils.. it's a bit overkill and is hard enough to do the first time. The easier the better. It stays put as is like it is without all the added help.

Disconnect your battery FIRST!