Hello! We just purchased a home and I am in the process of prepping walls before I replace trim and paint. I removed the baseboards and casing. The previous owners had done a quickie job and it appears that they used the same paint to cover trim and walls (no separation between the two, just painted it all together). The walls are in ok condition, the finish is relatively flat compared to the shiny trim. The paint on the trim could easily be scratched with a fingernail. It didn't matter because I was replacing the trim anyway. However, I have this large opening from living room into the kitchen. I was going to sand down the 1x4 that lines the inside of the opening to remove the shine but as I am the paint is peeling off and is almost rubbery!
I want to know the PROPER way to remove the paint and then how I need to proceed. I am assuming prime and then use a quality paint. I just really don't want to screw up the prep and have this happen again!

Thank you!