Dropbox provides synchronisation and backup features over the Dropbox Internet service. The Dropbox client application is available on Windows, Mac and Linux. If you no longer plan to use Dropbox on your Mac or have cancelled your account, it's a good idea to uninstall the Dropbox client to free up space and memory resources. Mac OS X does not include a central feature to uninstall programs, which means you will have to manually remove Dropbox.
Click the "Dropbox" menu at the top of the screen next to the clock and select the "Quit" option. You can skip this step if Dropbox isn't running.
Click the "Finder" icon in the Dock to open a new window. Click the "Applications" shortcut on the left side of the window to enter the Applications folder.
Locate "Dropbox" in the Applications folder. Then drag "Dropbox" to the Trash icon in the Dock to delete it.
Click "Macintosh HD" in the left side of the Finder window. If you've renamed your system hard drive, click its icon instead.
Open the "Library" folder, then the "Contextual Menu Items" folder. Drag the "DropboxHelperTools" folder to the Trash icon in the Dock.
Click your user name in the left side of the Finder window to go to your home folder. Drag the "Dropbox" folder to the Trash icon in the Dock. If you want to keep the files in your Dropbox folder, skip this step.
Press the "Ctrl" key and click the Trash icon in the Dock, select the "Empty Trash" option and click "OK."