I know this is dump question, but google talk on N810 seems always connected and I have no way to exit the program unless I reboot it.
Any one?

Thanks.

If you click on the Presence button in the status bar > accounts settings > uncheck the google accounts you want to turn off > close this will solve your problem and allow you to still have other accounts active.

Well, this will only allow logoff from the server, but what I want is to completely shut down the process.

If you want to completely remove the Google talk client from appearing on the N810, delete the account. Do the same thing as mentioned above, but instead of unchecking the Google talk account, select it and click the delete button.

Just to make sure we're talking about the same thing here:
What process? In other words: When you're not connected, what is it that tells you there's something active that's related to Google Talk? (Because probably this would be what you want to get rid of.)

The reason I ask is that Google Talk connectivity is not one single application; it's only one part of a framework that handles everything chat/VoIP-related. I'm not sure how far you can go removing anything related to this framework, so it would be helpful to know what exactly you want to get rid of.

Well, when the process is running, it has small icon on the applet bar(green dot when it's online or red if offline), it indicates the process is running. I belivee it uses some resourses even if it's at online state.
Say Skppe, it completely shuts down after quit, or all other applications such as browser, etc.
Remove account or disable account will not kill the process itself as I can see the icon is still there.

AFAIK this icon is only an interface to the settings, not an indication of the running process.

So when you do what Nelson L. Squeeko said above (delete the account), you should have removed everything that could really eat up resources.

You could still remove the icon from its position completely if you really wanted to, but IIRC this requires root access and editing the text file that makes this icon permanent. I'd neeed to have access to my tablet to tell you exactly how this is done.

IIRC, if there are no accounts defined, the connectivity icon doesn't show up at all. In other words if you delete all your accounts the "red dot" will disappear.