Now, you need to add a wire to short, we will let you short or open a device later.

Hi RiccardoAF, Are you asking how to: i) show a short circuit (a shorting link or jumper) across a resistor in a schematic or: ii) short out a resistor in a simulation schematic? If (i) then you could place a 2 pin header and wire across the 2 pins. Or you could create your own symbol to represent a shorting link. If (ii) then you can use the static switch symbols from the EasyEDA libs and set the state of the switch to ON or OFF. Or you could use a voltage controlled switch driven by a voltage source. Or see: <https://easyeda.com/bbs_view_1701.htm> for a way to create a time-controlled switch and more general information on controlling switches in EasyEDA. Note that you cannot set a resistor (or the resistance of a switch) to zero. The resistance can be small (e.g. 1e-3 Ohms) but it must be >0.