A client recently asked me this question, and despite being a straight forward query I really struggled finding a resource that explained how to achieve the outcome I was looking for.
Depending on the theme of your Facebook Page and which settings you select, Facebook will recategorise it as a Page. I suppose from their point of view, it make sense to separate local businesses and services. Their approach to business is different to, say, an ecommerce website. Plus, it's useful data for any future product launches. We've seen with Marketplaces just how seriously they take local.
However, I personally know a few people who never wanted their Page to be a Place. They added the address of their HQ just because Facebook asked them for an address. In doing so, every time they go to select their Page in Ads, it's always under the Places category. Does it make a difference? I've not noticed any, nonetheless maintaining valid data is always a good idea.
So, here's the process to convert your Facebook Place back into a Facebook Page.