Drop A-Level Business for Geography 3 Weeks in?

Ps. my other a levels are maths, further maths and economics

Yes, if you're already doing economics. Business and economics are sometimes considered overlapping subjects by some unis (although I argue they're too dissimilar to be), whereas geography is not (even though there are various sections in human geography that looks more into economics and business than in the other subjects).

On the other hand, there is no sense in doing 4 A Levels if it's affecting your grade and you don't need to do so. I would think through whether you're OK handling that many A Levels and getting high grades in all of them (assuming you're applying to top end unis considering your subject choices).

Is further maths considered a top uni targeting a level?