Is it safe to "cap" a disconnected doorbell wire using electrical tape?
Doorbells in Europe use mains voltage.  The far better way to do this is to disable the supply transformer or other voltage source, or disconnect the doorbell at the transformer if it shares the transformer with the furnace/thermostat.  

For that matter, nothing keeps you from putting the doorbell transformer or other power source onto a cord-and-plug connection, and then stick a lamp timer into the socket.  Now the doorbell will only function the hours you specify.    You can put a sign on the doorbell to this effect.