The best method would be going doing a test patch with various chemicals..... that's the norm when pricing up a job
It could be one of a hundred variants of paint and posting a picture on here is a bit like trying to guess the lotto numbers for Saturday without knowing what kind of paint it is or any other info, however DCM striipers do the job 80 percent of the time, 15 percent would be via enviromose or similar, and if those 2 fail then an abrasive method would usually do it, ie wetblast or similar