In most cases, when a garage door opens or closes by itself the problem is due to a short somewhere. This short is most likely to be in one of your transmitters or in the wall button or its wiring.
A short in your transmitter causes a continues signal to be sent. Remove the batteries from your transmitters and try operating the door from the wall button. If the problem is intermittent, you may want to do this for a few days to eliminate the transmitters as the source of the problem.
If the problem persists, try removing the wall button wire at the motor head to ensure it is not a short in the wire to the button, then try operating the garage door with the transmitters only. If it stops the problem, replace the wires and test the wall button. It is a process of elimination.
The key is to eliminate where the short is occuring, whether it be in one of the transmitters or the wall button.
Feel free to post any follow-up questions you may have.