I wish. That seat and the structure of the Security Council is in the UN's charter. You need a new UN to get rid of Russia and put the correct China back in place.
The UN has not resolved that the Russian Federation is the Soviet Union w.r.t. veto powers. It's just been assumed. For the PRC there was an actual vote.
Ukraine legally has just as much of a right to the Soviet Union veto.
I mean, no. There is no such thing as international law as there is no superior power to forcibly require compliance. However your statement and the argument within fails fatally at a fundamental level as you simultaneously acknowledge the lack of a formal framework of hierarchy while appealing for that absent hierarchy to act.
There is no formal framework, it's simply an exercise in power, and the anti-Russia nations hold enough power to redefine how they act with respect to Russia (i.e., dismissing them from the Security Council or simply ignoring their attempts to veto). Just because the rules are not naturally enduring has no bearing on their ability to have an impact while the majority powers support them.