I have a wanted level of five and I'm wondering if there is a way for me to completely lower my wanted level back to one?
There are three ways of lowering your heat level in Undercover:
Visual customisations such as paint, vinyls and aftermarket parts. The more you apply, the more 'unrecognisable' your car becomes.
Swapping cars. If you use another car for a while, the heat from your first car will slowly subside.
Avoid tangling with the police. Essentially, that means turning tail if you see one on your minimap, or ducking into a place where they don't have line of sight of you. If you manage to avoid the police for a while, they'll 'forget' about you.
At heat 5, you'll have much better luck with the first two than the third.