This is a tricky question because although imperialism in the pre-WWII sense is gone, there are still actions by nations around the world that are reminiscent of imperialism. Following the end of WWII, European powers had largely divested themselves of their colonial holdings (although the process took several decades). Japan was defeated and lost all of its holdings throughout Asia (but still retained its emperor). The American nations were independent, save a few areas, and African nations were either independent or on their way to independence. Thus, imperialism in the classical sense—direct rule from a foreign power abroad—had ended.
However, countries can still be highly influenced by foreign powers. The US is often pointed to as a "neo-imperialist" power given its economic, military, and political might. There are hundreds of US military bases around the world; the UK, France, and Russia also have multiple bases in foreign countries. The US retains the role of de facto military for countries throughout the world, including many throughout the Western Hemisphere. Costa Rica and Panama, for example, do not have militaries but instead rely on the US for their defense (the US also maintains a large presence in Panama to protect the Panama Canal).
It would be foolish to think that this military presence does not have an influence over a nation's politics. But this is a relationship that costs both sides: Forfeiture of some aspect of national sovereignty for one, and the expenditure of money and military personnel for the other. With a military presence also comes economic growth, jobs, and a better standard of living for local inhabitants.
But militaries are only one way a country can have a neo-colonial influence. The other way is through economic expenditures. China has been increasingly accused of neo-colonialism in Africa, as it has become the biggest trading partner for numerous African countries. China has also been accused of taking resources from Africa while providing substandard infrastructure projects in return. Likewise, there has been a flood of Chinese laborers to African countries that have poor border controls, while cheap Chinese exports have driven out African competition.
If powerful countries like the US and China were to pull out militarily and economically from smaller countries abroad, what would happen to each? Smaller countries would more than likely be worse off economically and perhaps at risk from hostile neighboring countries. Powerful countries, meanwhile, would lose influence as well as access to natural resources within those smaller countries. Therefore, although the era of imperialism is over, the relationship between powerful nations and smaller ones continues in a patron-client manner because both get something out of it. In some respects, imperialism can be viewed as a historical reality even if we don't use the word "imperialism."