Abolish

I believe that they should abolish the "first past the post" system we use in Parliamentary elections.  The new system doesn't have to be unstable.  We could replace it with something like the German system, where about two-thirds of MPs are elected in the same way as now, while the rest of the seats are allotted to match each party's share of the popular vote.

They should also abolish nuclear weapons.  The United States should have made a bigger effort to do so in the late 1940s when they had a monopoly on them.  The Truman Administration actually did make such a proposal to the United Nations, but stipulated an inspection system that was ahead of its time to the point of naivete. (Stalin was never going to agree to that, and the Americans probably knew it.)

I think it was Ian Shoales who said, "If I were American president, I'd get rid of all our nuclear weapons.  That's why I'll never be elected President."

But I mostly think in terms of all the new things I want created rather than things to remove!  Like, I think they should introduce a tax on stock speculation and currency exchange.  Not only will it provide money to build infrastructure, it'll probably make the financial system more stable.