God can do whatever He pleases. We do not dictate to Him, He dictates to us (He has even given us His written Word). As Paul wrote:
Romans 9:20-21 Nay but, O man, who art thou that repliest against God? Shall the thing formed say to him that formed it, Why hast thou made me thus? Hath not the potter power over the clay, of the same lump to make one vessel unto honour, and another unto dishonour?
And as Isaiah said:
Isaiah 45:9 Woe unto him that striveth with his Maker! Let the potsherd strive with the potsherds of the earth. Shall the clay say to him that fashioneth it, What makest thou? ...
The evidence of God, the Creator, is plain to everyone. There are people that will the deny the evidence until it is too late (i.e., at the Judgement).
Romans 1:20-22 For the invisible things of him from the creation of the world are clearly seen, being understood by the things that are made, even his eternal power and Godhead; so that they are without excuse: Because that, when they knew God, they glorified him not as God, neither were thankful; but became vain in their imaginations, and their foolish heart was darkened. Professing themselves to be wise, they became fools,...
The God deniers aren't looking for evidence, they are justifying their denials.
He already did this and they still don't believe Him, as this opinion demonstrates.
There is nothing left for Him to do.