Cleaning paint is one of those jobs you do. It's tedious, time consuming, and need hard work. Fortunately, tools are available to make the job easier.
Your first weapon is a chemical paint remover, especially for stubborn old coats of paint. You may shop paint stripper at https://panelstore.co.nz/products/premier-pbs-paint-stripper-1ltr.
There are many brand name erasers that are very effective and easy to use. However, you must wear protective clothing. Rubber gloves, long sleeves and pants, and protective glasses are required. Spread newspaper or plastic sheets nearby to prevent spills.
Using an old brush, apply a coat of free stripper and let it run according to the manufacturer's directions until the paint softens. Then it is relatively easy to scrape off the paint with a paint stick or a razor.
When all the paint is gone (I mean everything, don't be lazy here), clean the wood with cold water or paint thinner. This will neutralize the chemicals left by the stripper.
Another tool in your arsenal is an electric paint remover. This is a handy little scraper with a built-in heating element. The element heats up when ignited and keeps the tool a certain distance from the paint, which makes it softer. I think this tool is more useful for small, stubborn paints than for large areas.
When all else fails, gas or kerosene burners work really well. Be careful when using one of these criminals. All flammable materials must be removed from the area immediately.