Confused about what?
The center brace on the tank gives more support to the glass. Without it, if it is needed, the glass will eventually begin to shift and your tank can basically collapse. Cutting it out is not a smart idea.
I don't really undewrstand how your tank brace is in the way of the lighting. This shouldn't make much of a difference. If you are that concerned, you can hang the light or use mounting legs to raise it higher, like already suggested.
This is an example of a light with mounting legs. Basically it just lifts the light up a little:

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Current setups: 1800 gallon koi pond, 10 gallon planted, 150 gallon reef, other FOWLR tanks