Problem is that you have set yourselves up as the world police. And you can't just suddenly drop a responsibility that you have taken without leaving an awful mess.

For example, a large number of countries have foregone developing a nuke since they are under the US/Nato nuclear umbrella. Remove the umbrella and you get a whole bunch of new wars, and also many more countries feeling the need to develop a nuke.

I don't really like the US hegemony and the financial system it is based on, but I prefer it to Mad Max world.

Fine, clean up your act, and avoid CIA ops to overthrow governments and run drugs etc. But pull out of the other things very carefully. 

 Most wars since 1945 have been proxy wars, with both sides funded by a Great Power.

"World Police" are just as unaccountable, lawless and self-serving as the very worst domestic police, and for the same reasons.

If instead every village had a nuke, wars would be few, brief, and used as talking points for generations.

(Nuclear Winter was always a lie. )