Look in the Home > Concrete link under Browse Projects, at lower left, for previous similar questions and answers, many of which include ballpark costs. Generally, assuming decent access, in the ballpark of $7-10/SF likely, including removing and disposing of the old concrete. You may be able to cut your cost a buck or two per SF by just having them break it up into chunks and setting them aside, for you to use as pavers or planter blocks in your yard, if you have such a use - note there will likely be wire mesh sticking out which you will need to snip of and hammer flat, or bend under, for safe use.
Fancier patio concrete, including stained or embossed, more typically $10-20/SF - probably in the upper half of that range for your small job.
