Whenever you save files to a specific location on your Mac, OS X will save this location in a “Recent Places” listing which will be available the next time you save another file. This feature allows quick access to the folders you commonly use and hence saves a lot of your precious work time.

By default, the recent places list will show you the past five most recently accessed folders. Now, while this may be convenient for some, it can become annoying, especially if you would just like to clear an item or the entire list. …..

Full article here:
How to Clear and Manage “Recent Places” In OS X (Make Tech Easier)