Can Flash travel through time?

Yes, it is simply the movement of objects following the curved lines of that depression of space-time. For this we can compare it to the "grandfather paradox" which states that every

change that the time traveler makes in the past there will be consequences.

The reason Flash can travel through time is because he is traveling faster than the speed of light.

According to Einstein in the theory of special relativity, "the laws of physics are invariant for any observer moving freely, regardless of the speed at which he is moving."

"The speed of light is an upper limit to the speed of any project." In other words, it is almost impossible for anyone to travel faster than the speed of light.