Yes, that does look like an ODB plug thats been cut off. If you look more closely, the wires nearer the connector are damaged too, so I think it was cut off to prevent these shorting out. But, that does mean that you cannot read any codes, and also cannot reset anything!
Also, for those not in the UK (the OP is in Greece) the ODB socket is indeed by the fusebox, inside the left hand front door. In the UK, the ODB port is inside the right hand front door, but the fusebox remains over at the left side of the car.
View attachment 434990