Unfortunately if you do that the plates are no longer legal believe it or not.
Here's what the DVLA rules say:
The British Standard sets out the physical characteristics of the number plate. This includes visibility, strength and reflectivity.
The British Standard also requires each number plate to be permanently and legibly marked with the following information:
* The British Standard number (currently BS AU 145d)
* The name, trademark or other means of identification of the manufacturer or component supplier (The company that made the plate)
* Name and postcode of the supplying outlet.
My plate was manufactured by bestplate, it has the dealer name and postcode on it in the middle and on the right it says bestplate BSAU145d. Does this mean i'm not allowed to cover the dealer name and postcode up?