Let it sit
The first thing you are going to want to do when cleaning your freezer is to turn it off, and let it defrost for a while, this will allow all the water to run out of the freezer as well. place the freezer in a safe location when you do this, so you do not damage the floors with water damage.
Sometimes this defrosting process can take too long if it is just done naturally, but there are one or two ways to speed up the process. One of these it to get a bucket or bowl of boiling water and place it in the freezer with the lid closed, this will allow the steam to be caught inside and could speed up the process. Also using a hairdyer on a reasonabl y low heat can also help.
When most of the water has been drained, use either simple dish washing dtergent or even baking soda and vinegar have jhad positive results. This detergent must be mixed with some water and you can use a cloth to clean your freezer. Once this is done then rinse the entire freezer, and wipe down. When you are restacking your freezer make sure to check all the meat before you put it back in, sometimes we forget how long we have had some items.