Right turn light problem

The right turn signal light on my 2003 Subaru Baja does not turn off even after the engine is off. I have to disconnect the battery to turn the light off. I sent it to an auto repair shop and they could only identify that there is something wrong in the steering column and they had to refer me to an anto electric shop. What could be the real problem?

Possibly a defective multifunction switch, or wires shorted together

Is it relatively easy to fix? How to replace the defective switch or shorted wires? Thanks.