Hire a professional. As an insurance agent in California, I am required to take continuing education classes for my license renewal. One of the classes I take from time to time is on Mold Remediation. Some types of mold can be very toxic to some people, and in some cases has caused death. Every time you sand to remove to mold you spread the spores to other areas where they and grow. It may cost more but you will have a record what was done and by who. Service Master is a company which is used by most if not all of the insurance companies I represent, and they may be in your area. Also for your own protection, you should wear a good mask/filter when working around it. It is not, in my opinion worth taking a chance on, protect yourself let an expert do it.