moderate control of aphids can be gotten by washing them off with a water hose, putting them where wolf spiders and ground beetles can catch then.
For heavy infestations, use a systemic insecticide like Bayer Tree & Shrub
Get rid of the aphids and you'll likely take care of the sooty mold issue as well. As Walter says, usually a good blast of water will do the trick.
You can use a mix of Dawn dishwashing soap and water in a spray of any kind. Because I have a lot of Roses, I use a garden sprayer container with the pump on top.
Be careful using detergent on plants. Soaps and detergents are not the same and dishwashing detergent may harm plant leaves by dissolving the wax that protects them.