Can 15 mm stone calcium oxalate be dissolve naturally?

No: Calcium oxylate stones cannot be "dissolved". Although they vary in density, there is not a chemical (either natural or medicinal) which can be ingested that will dissolve them. A 1.5cm stone in the kidney is best treated by eswl (shock wave lithotripsy).

Kidney stone.: Kidney stones up to 5mm in size will predictably pass on their own. You would just drink plenty of water so you produce a lot of urine, dilate those ureters and allow the stone to pass. It may hurt while it's on its way out, but it'll pass. A 15mm stone isn't going anywhere, and if it decides to try to leave you it's going to get stuck. You need a Urologist.