Depends on the type of metals. The body generally releases metals like it releases most things. Through sweat, respiration and excretion. Heavy metals only have a real effect if they reach toxicity levels in which case they do some real damage. Mercury for example becomes toxic when you have around 1 gram in the body. At this stage you get mercury poisoning which can be lethal at the extreme, and at the minimum it can lead to health problems. Pretty noticeable symptoms though.
There's only a few manual ways of removing mercury from the system. All of them are expensive and dangerous and are only recommended if mercury poisoning is confirmed and could cause a major problem (major neurological damage)
Generally mercury slowly works its way out of your system over a few weeks. People are continuously exposed to mercury through air, food, water and other items. If you get too much mercury exposure the mercury builds up in your kidneys and brain where it will tend to stay for a long period of time (it'll leave eventually). This is the main course of mercury poisoning and is why they advise that you don't over expose yourself to levels of mercury. But unless you're working in an area with heavy mercury leakage then you shouldn't have anything to worry about.