Move the vinyl trailer top to a sunny location. Allow it to sit in direct sunlight for three to five hours to kill the mold spores and dry out the surface.
Sweep the dead mold spores and any other dirt or debris off the vinyl trailer top.
Pour 1 gallon of hot water into a bucket. Add 1 cup of bleach.
Wear rubber gloves to keep your skin from drying out due to contact with the bleach solution.
Dip the scrub brush in the bleach solution. Scrub the vinyl trailer top, starting at the top and moving down. Rinse the brush, as needed, then continue to scrub the vinyl surface until the mold has been removed.
Rinse the vinyl trailer top with a hose. Begin rinsing at the top of the trailer and move down to ensure the entire surface has been rinsed.
Dry the surface with cleaning rags to remove excess moisture. Allow the vinyl trailer top to air-dry completely while sitting in the sunlight.