The presence of two red rear reflectors on a car used on the public highway is a mandatory requirement in the UK and is also a requirement under the UK MOT. Therefore, modifying them in a way that reduces or eliminates their effectiveness such as wrapping them or removing them is a no-no IMHO; doing so could also invalidate your insurance.
Also, if you’re stopped by the police and your rear reflectors are either less effective than they should be or have been removed completely, then the consequences could range from;
a) best case scenario; a polite warning to reinstate them back to original factory spec / condition
to
b) worst-case scenario; a fine and / or points on your licence.