Hi,
Just to make sure that we're talking about the same thing: With inline styling, you mean that in the HTML you see: style="some text"?
If so, the easiest way is to use a find and replace operation. You can completely remove the styling, but you can also change certain styles with classnames so you can use your css. To do this, you obviously need to know a bit about HTML (as you probably do). Backup your project before doing anything like this though. You can wreck your project in seconds.
If by inline styling, you mean styles selected from the style chooser menu, you must see something like class="some text", you're in luck. Don't bother with this, leave it be. If your style sheet doesn't containt a style definition for this class, the default style for the element will be used. For instance:
If a regular paragraph is 10 points bold, you may have a paragraph with the class unbolded. (In HTML <p class="unbolded".) It there is no style definiotion for the paragraph unbolded, the paragraph will be styled as a regular paragraph. If the paragraph is incorrectly styled, simply remove the corresponding style (p.unbolded) from your css.
Greet,
Willam