None of the responses I'm seeing here even mention the Human Interface Guidlines produced by Apple. There is a section therein called "iOS UI Element Usage Guidelines" that all iOS developers should have under their pillow.
To summarize "Tab Bar" from the HIG, "A tab bar gives people the ability to switch between different subtasks, views, or modes." Following a short introduction, you will see a section titled "Guidelines" that completely outlines the dos and don'ts of tab bar usage.
Granted there are many apps (iOS and otherwise) that break these conventions, and some for good reason. The first thing I would ask myself is "Does the usage of a tab bar comply with Apple's recommended design patterns". If it does not, the solution is probably found elsewhere. However, if the answer is yes, I would then examine exactly what motives you have in stripping it. There are good reasons. Just make sure your really know what yours are before you break something that just about every iPhone user is accustomed to.