To remove stubborn dirt from plastic frames use a combination of warm water and dish soap mixed together in equal amounts. Finally, add trim around the edges of your window to finish off the look!However, there are a few extra tips you should keep in mind during this process. It's advisable to (regularly) maintain your windows to ensure their longevity!Here are some tips for doing so: Clean the window frames with a soft cloth and mild detergent. And don't forget about inspecting for moisture damage; if it's present then consider using dehumidifiers or waterproof sealants beforehand.