An easy way of getting rid of hickey's in one day is to take a spoon and wrap the spoon in a piece of cloth and then gently rub the hickey with the spoon and cloth.
This will help reduce the swelling of the hickey and cause it to go away.
You can also wrap some ice in a cloth and then apply the ice to the hickey as the ice will reduce the hickey overnight.
Another option for getting rid of a hickey is to use some peppermint based toothpaste and apply the peppermint toothpaste directly to the hickey and leave it on the hickey and it will tingle for a bit and eventually the hickey will go away.
After the toothpaste stops tingling then you can wash the toothpaste off and you may have to apply the toothpaste a few times for the hickey to go away but it will work.