It is impossible to disprove the existence of God. The only way you could do it is if you were omnipotent, omniscient, and omnipresent, so that you could be absolutely sure that there isn’t a greater being out there able to hide their presence from you. Problem is, if you had those powers, you yourself would be God, and it would be a self-contradiction at that point to try and disprove your own existence.
