LED bulb still emits light when turned off
There are two possibilities the switch is inserted:


Switch switching the voltage line.
Switch switching the GND line.








simulate this circuit &ndash; Schematic created using CircuitLab

The capacitors shown in the circuit are the capacities the (more or less) long lines form to GND.

If the 2nd circuit is what you have the lamp always is connected to alternating voltage.
In that case there is a possibility of some very low alternating current flowing via C10 to GND even if the switch is open.

You can find out if your configuration is the 2nd circuit by testing with a one-contact neon test light. It is the case if the test light lights up when touching one of the two connections in your lamp socket even if the switch is turned off.