Sure, being beyond all dimensions would mean you are likely beyond the physics and laws of any given dimension, but the whole point of absolutes is that they are independent of such factors. For example, Physics Manipulation would likely differ based on the user's dimensionality, with lower dimensional Physics Manipulation being both incapable (or at least less capable) of affecting a higher dimensional being, and superseded by higher dimensional Physics Manipulation. However, the absolute version of Physics Manipulation, Omni-Physics Manipulation, can, by definition, manipulate all forms of physics, including those in higher dimensions. It doesn't matter if it's user is in the third dimension or the tenth, or even beyond them all, the capabilities of Omni-Physics Manipulation remains the same.
The same goes for other Absolute powers. Absolute Erasure can, by definition, erase anything. If it couldn't erase something in a higher dimension or beyond all dimensionality, it wouldn't be absolute, and nothing about the definition of being beyond all dimensionality suggests that BDP could survive a power that can erase anything and doesn't care about dimensions when doing so.
Same with Almighty Laws. The whole point of them is that they apply to absolutely everything and cannot be bent or broken. They aren't limited to a particular dimension, dimensional level, reality, universe, etc, as the laws of physics or a dimension might be; They are absolute and apply to everything.