Burning smells such as melting plastic or burned wires, can be a clear indicator that the electrical component in an appliance or your home wiring could be failing. Noticing this smell and acting on it quickly can be the difference between a small issue and a more dangerous concern.
If the smell is coming from an appliance:
Unplug the unit and discontinue use
If the unit is old it may be time to replace it
Call the unit’s manufacturer to see what your best options are
If the smell is coming from an outlet/power point:
Unplug anything in the outlet and discontinue use of that outlet
Call a Service Today Electrician to come and check your wiring and resolve the issue causing the smell before it turns into an electrical disaster
DO NOT attempt to remove the power point cover to see what is going on. Electricity is  a dangerous form of energy and should be dealt with by a licensed professional ONLY.