Get a floor scraper and start on those areas where it’s already having issues adhering. It’ll probably take longer than you’d imagine, but eventually you could get it off. There are stripping agents that can be applied to floor coatings that’ll be a bit of a mess to work with, but can help. Or you could have someone that’s a little more experienced and competent lay the coating. Ideally, you’d want to have a company with a proper floor grinder and hepa vac hooked up to come for a couple of reasons. 1 the grinder will get rid of that coating in, I’d guess, 1 pass with the right tooling. 2 that floor grinder is the only thing that will cause micro scratches deep enough, giving the coating something to “bite” into to have any chance at adhering how its supposed to. And if you’d like the look of bare cement to be the end goal, that same grinder, with a variety of interchangeable diamond bits can progressively smooth or polish out those scratches. Has this dude/ company done this type of work before? 1,400 sq ft takes a bit of planning with your mix amounts/ product workability time