If I understand your question, you are looking to be paid to clean out properties? If so, you need to find the people in control of getting them cleaned out. Those folks would be the Realtors who list them for the banks or the Investors buying the properties. You can meet them at many different local Investor Club meetings. Ask for work but don't expect to be paid until your services are complete.
Many of the city services are available by calling 311. You can also make a requests using online 311.
Specific information about waste desposal is located at the public works website linked under web references.