Why Can't Obito remove Tobirama's Mark?

[Nidds]

Prior to him being a sage, he was marked by Minato, but after Minato's mark disappeared (Tobirama eventually marks him again)

With that being said, I wonder why Obito can't remove Tobirama's mark (or he did and I didn't see it)?

Obito can theoretically nullify all ninjutsu

FTG is technically Space Time Ninjutsu

According to this scan, Obito can nullify all ninjutsu based techs

Spoiler

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So, I wonder what gives? He's basically a walking punching bag if he doesn't remove it.

 

[UchihaNagashi]

Maybe he doesn't give a flying sh*t. Why would he care? He can own them already anyday.

 

[Sennin of Logic]

Maybe sealing is a variation of creation of all things. It might be to complex for him to rip apart.

 

[pateuvasiliu]

Isn't the FTG seal fuinjutsu, rather than ninjutsu?

 

[Nidds]

Maybe he doesn't give a flying sh*t. Why would he care? He can own them already anyday.

Not making much progress with that except getting rid of one of Minato's arm

 

[Henrik]

Plot no jutsu

 

[EggesGabo]

he marked him when he became the jinchuuriki unlike Minato. thats what i think..

 

[PureSkillz]

The ftg seal isn't ninjutsu. And he would probably have to hit himself with the black ball to remove it........

Minatos seal only disappeared when Obito absorbed the Juubi