What input method are you using? Are you using the Swype Keyboard? If so, then I can try to help you. I've added misspelled or nonsense words to my dictionary all the time! Here's what I do to remove the misspelled words from my dictionary. Type your misspelled words (in your case "yiu") in any text box, then select it by running your finger across the "Swype" key (the key with the S, i, and the hand symbol) and the "Sym" key. You'll then see a different keypad with arrows to move your cursor for editing purposes. Press "select text" button and then the back arrow key to highlight the word. Now click the "Swype" key again. You should see a popup window asking you if you want to delete the word "yiu" from the Swype dictionary. Press the "OK" button, then Delete the word that's highlighted from the text box. It should now be gone from your dictionary, and you can go back to your normal typing.
Hope this helps.