You can't remove the default messaging or the messaging icon, but you can change how things work enough to where your interaction with the default messaging app is minimal.
If you install Handcent SMS (or a similar messaging app):
- First, turn off all notifications on the system SMS app.
- Then configure your new app to handle the notifications.
Usually when you install one of these apps it clears the "defaults" for all messaging apps and you should be offered the opportunity to reset them. Failing that:
- Home - Menu - Settings - Applications - Manage Applications
- Menu - Filter - All
- Find "Messaging" and click on it. Under "Launch by default", "Clear defaults" (if you've set it to a different program, you'll have to clear defaults for that program instead - this is why I suggest having a minimal number of apps installed that do certain things; installing five SMS management apps would be ... unrecommended).
Next, once you have a text message "thread" on the phone, you can:
- Click on the "Messaging" icon on the bottom bar of the home screen (you'll still be in the default messaging app at this point, but bear with me)
- Click on a "thread" for a particular person
- That should offer you the opportunity to "Complete action using" all of the available apps that can handle SMS messages. Click on "Use by default for this action" and select the app you want to use.
The only times now when I end up using the default app is when I have no active threads and want to create a new SMS message - the default app handles that, unless you launch your chosen SMS app using a different icon instead of using the "Messaging" app.
Hope that helps!