Muriatic acid will do it,but take extreme care - it can be very dangerous to use
I would power wash it with a medium jet spray.
I wouldn't recommend it. Some of the chemicals in the alkyd will dissolve the latex and the alkyd won't "stick". It's best to remove the latex using laquer thinner or xylene first.
It depends on whether it is a water (latex) based paint or a oil based paint. If it is oil based paint it may not come out, but if it is a water (latex) based paint use 'Goof Off' or other latex paint removers with a wire brush. I have used 'Muriatic acid' on some concrete appications.
If it's latex based, you can try a product called goof-off.
i have dried white latex paint on car seat. what do i do to remove it?
Mixing a solvent into a latex typically ruins the product. Expected result is the latex paint turning into gel.
If I was going to repaint this, then I'd remove both the latex and the old oil base with a chemical stripper. Then re-prime it and paint.
You can not put oil paint over latex paint. Oil is a rigid coating and latex is a flexible coating. When you put a rigid coating over something that is flexible the rigid coating cracks off.
Possibly if it's latex paint.
The ingredient in glossy paint is acrylic. You cannot remove that ingredient.
Hot water
A sandblaster or sanding disc