Android - How to clear the keyboard autocomplete suggestions
This is positioned high in Google, so I'm gonna paste my solution here. I own a Sonyericsson Xperia Arc S and the Personal Dictionary list was empty.
The way to go was to go into the app listing (all apps), find the Xperia Keyboard service and Clear Data.
It resets every keyboard configuration, but it's how it works.
You can clear learned words under
Settings --> Language and keyboard --> User dictionary. Long press on the learned word and then edit or delete.
Go to setting ---> Controls ---> Language and inputs ---> keyboard and input methods --> (setting icon) behind your keyboard type -- > predictive text --> clear personal data .. :) That's all :)