From the net.
Ozone Generators -- Highly recommended by many, but an expensive option and you need to know what you're doing. These units should be used with caution as some are not suitable for use in occupied rooms, depending on the settings used and the knowledge of the user. Small ozone generators are often used to remove odors (especially smoke odors) from vehicles. Larger ozone generators are used for bigger spaces in homes and businesses. Ozone generators can also be used beyond general odor elimination but for more challenging problems like mold and mildew as well. If used in close proximity to a smelly guitar or case, an ozone generator might work wonders. One method would be to place the guitar and case in a small room (closet or bathroom or somewhere similar) with guitar free standing out of the case and the case open, then use an ozone generator according to the manufacturer's directions for the space in question. It might take only one treatment or perhaps several treatments. Ozone generators range from less than $100 USD to more than $1000 USD, so buying a good one can be a fairly expensive step to take. Ozone generators can also be rented, and you may also find a smoke remediation facility where you can bring your guitar and case for treatment. Note that ozone generators and ionizers are not the same thing, although they are often confused with one another. Do some research before taking steps involving ozone generators...but there are a lot of people who swear by ozone generators and their ability to remove odors from just about anything and their particular effectiveness in dealing with smoke odor.