Press the ALT key and use the mouse to select columns in the declaration part or in text editors. Texts marked in this way can be deleted or edited in one go, e.g. by typing in new variable names.
If the project cannot be translated due to syntactic errors or if there are other messages in the message window, you can systematically process the list of messages by pressing F4. CODESYS immediately jumps to the place in the source code belonging to the message.