Source: FANDOM Wikipedia

ZI-O Episode 30

Due to Geiz's refusal to play the part of his savior and some unforeseen circumstances, White Woz's future can no longer able to happen. As such, as a last-ditch effort to attempt to get Geiz to become his savior, he used the Another Blade Watch Swartz gave him to transform Amane Kurihara into Another Blade. He did so to deliberately force Kazuma Kenzaki and Hajime Aikawa to meet once more, knowing full well that their Joker nature will bring the end of the world.

Later as Woz, Geiz and Sougo make their way to Another Blade, White Woz intercepted the trio. Sougo decides to talk to him personally while Woz and Geiz go first. During their talk, White Woz admits that due to his future not being able to come into fruition, he no longer wants one to happen. Here, Sougo encourages him to not give up and to push onwards to the very end. An amused White Woz later return Zi-O II Ridewatch and Geiz Revive Ridewatch to Sougo and also gives the newly created Zi-O Trinity Ridewatch to him as well.

As Another Blade is defeated and the Blade Ridewatch is obtained, White Woz later stares up at Regulus in the night sky, awaiting his fate, when suddenly Black Woz meets with him where the two agree a new future is being written - and as a result of this new "Oma's Day", one of them will cease to exist, with Black Woz being chosen as opposed to White Woz choosing himself. When asked why, he confesses he failed to make friends unlike his counterpart, to his bewilderment. White Woz admits to liking Sougo, remarking he seems he'll make an interesting future, and requests his counterpart to take care of the young king. He also advises him to beware of Swartz and his future schemes. As he begins to slowly cease to exist, he wishes Black Woz's future to not be shrouded in darkness, and finally fades into the night sky.

The last words of White Woz to Black Woz before he faded away:

"I like that Demon King. He seems like he'll create an interesting future. Take good care of him. And be careful of Mr. Swartz. His schemes are greater than you can imagine ... Looks like it's time. I pray that your future is not shrouded in darkness..."

Btw this what Swartz looks like