Remove applications' icons to win back valuable space in your Dock. Get rid of dock icons of the applications that refuse to be removed. Quit the app whose dock icon you're going to delete, drag the .app file to the solution, enter the system password, and have the app being automatically edited to get rid of its dock icon.
Dock Dodger is a an application that lets you manage your dock icons. It can be used to remove any application's dock icon permanently. This is perhaps most useful with apps that don't let you disable the dock icon from their settings window. Basically, what Dock Dodger does is edit the application to remove the icon. With most applications, this works like a charm and it is really easy to do. To remove an app's dock icon, you simply have to quit it and drag the .app file to Dock Dodger. It will ask for your system password, since it will be editing system files. After you enter the password, almost instantly, the app will edited, and the next time that you run it, you shouldn't see a Dock icon. I have seen some side-effects in some applications. For example, the menus became disabled as well or some app couldn't run. But most applications work well after being edited. However, the website has a big warning about using this app and it recommends that you use it on a duplicate of your applications.
If you eagerly need to remove an application's dock icon, Dock Dodger can do the job. It is a donationware app, so make sure you donate if it has worked for you.