To get rid of baseboard heater smells turn the baseboard heater off and allow it to cool down.
Then remove the cover to it and gently and carefully clean the interior surface and outside surface as well to remove any dust and debris and use a vacuum cleaner to suck up any dirt that can't be easily wiped away.
You can also use a damp cloth with some vinegar and water or dish soap to clean the baseboard heater and heating element.
Also opening of windows can help the smell dissipate.
Baseboard heaters are safe when used properly and as long as you keep them clean and keep anything flammable including curtains, clothing, furniture etc away from them.
Both electric baseboard heaters and the radiator type baseboard heaters are safe to use and have been used safely for many years.
When your electric baseboard heater smells like burning plastic it could be dust and debris accumulating on the heating element or something plastic may have gotten lodged in the electric baseboard heater.
Other reasons for an electric baseboard heater smelling like burnt plastic are faulty wiring, loose wiring connections overheating components and if it's a new baseboard heater the burning plastic smell could be the protective coating burning off.
If your electric baseboard heater is clean and free of any dust on the heating element it could be a loose or bad wiring connection or a wirenut is loose on the electric heater.
If the burning plastic smell goes away pretty quickly then the heater is likely safe but if the burning plastic smell persists with your electric baseboard heater you should shut it off and have it checked out to be safe.
It is normal for an electric heater to smell burnt when you first turn it on after it has not been used for awhile.
When an electric heater sits unused for awhile it can accumulate dust and when you turn the electric heater on the heater can emit a burning smell due to the dust being burnt off.
This is normal and should go away within 10 minutes to 30 minutes or so but if not then it could be a sign that the electric heater is bad and needs repaired or replaced.
Even a brand new electric heater may smell burnt for a bit when first turned on due to protective oils and paint during the manufacturing process.
But the electric heater should not keep smelling burnt for too long or it's a sign that there's a problem which could result in a fire.
The burnt smell of the electric heater when just due to dust or the newness should fade away after a couple of minutes to a few hours and if not it could be a more serious issue.
A burning electrical smell is a more serious issue and can indicate overheating, damaged wiring or other electrical problems.
If you continue smelling burnt electrical smells it the heater should be turned off and unplugged or power cut off to it.
My electric baseboard heaters will emit a dust burning smell at the start of the season when I turn them on for heating as there can be dust that I cannot fully get out but it eventually burns off.