Disable or sign out of Google Talk? I have a Sony Xperia X10 Mini. It keeps annoying me with Google Talk notifications, although I already went to "running services" under Settings/Applications and cancelled them. How do I get it to stop?
The easiest way:
If you'd rather not receive notifications, you can disable some or all of them.Here's how:


Click 'Settings' at the top of your Friends list.
Highlight 'Notifications' along the left side of the Settings
window.
Uncheck the boxes next to the notifications you don't wish to
receive, or check the box next to 'Disable all notifications.'
Click 'OK.'


Source: https://support.google.com/talk/answer/24742?hl=en

Alternative methods:

If you're running Jelly Bean, you can go to the app details, disable the app and uncheck the option to show notifications. Click here to see how.

If not, you can do one of the following things:
Root:
Root your phone and install Titanium Backup. You can uninstall Google Talk so it won't bother you again.
Non-Root:
Delete the app by running an update script which removes the app. Click here to view how exactly. You should only delete the /system/app/Talk.APK.