1. Enter wrong pattern 5 times and wait for 30 seconds.
2. Select "Forgot pattern" and enter your email account username and password.
3. Make sure you use the same account that was used to activate the device and double check the password by logging in to that email account in a browser.
4. If you don't have access to the original email account, you will need to do a hard reset and loose your settings and apps on the devcice. The data on the memory card will not be wiped though.
Note: if you can't remember your email password, you will have to visit the email service support page to get it reset.
also, see here...
or here... http://mytabletguru.com/forgot-password-pattern-unlock-of-android-tablet/