If it has been over watered consistently for a long period, then you can certainly attempt to reverse the damage. However, your level of success will depend on a few factors such as how long it had been over watered for and what the level of damage is to the root system.
If there are still some green leaves that look relatively healthy (even if only a few of them), then you have a good chance of reversing the damage.
Just reduce the amount of water, and trim off any obviously dead shoots. If the damages to the plant from the overwatering were not too extensive to the root system, then you should see the plant start to bounce back in the coming week or two.
If it was only over watered once, then you can try to drain any standing water around the plant and allow the pot the plant is in to drain. If the plant is otherwise healthy, one overwatering will likely not hurt it.