This one cannot be known for sure. The surest way is to confirm with another sleep test to see how much snoring and sleep apnea have decreased, for example if your AHI (Apnea Index) falls below 5 breaths per hour. The doctor may diagnose and stop using the machine.
Alternatively, try downloading the results from the cpap machine. If the pressure is running at the lowest value of 4 cmH2O all the time (it should be tested for a while to be sure) with the AHI not exceeding 5, the machine can be stopped.
Or another way, simple but not very accurate. That is, try to stop using the device. Then look at the symptoms, for example, let the person notice whether there is a sound of snoring or stopping breathing. Did you wake up with a headache? In the middle of the day, I feel like I'm not full. Are you asleep or not, etc.