how to get read of 'abc' icon on the top rigt corner of my Blackberry screen

In a message

Hit Menu>options>Enable Suretype

Or you can try

Option>Language>Input Language - English (United States)

1. Go to the main applications view on the Pearl.
2. Choose Options (it's the little crescent wrench icon) and select it.
3. Scroll down to Language and click the trackball.
4. Under "Input Language" you want to either select your language with Multitap (to enable Multitap) or without (which puts you into SureType mode). For example, I selected English (United States) to get SureType.
5. Now just click the menu button and select Save and you're back to normal.