Log into your CLU account.
Click ont the gear icon, located in the top right.
Select Settings and click the Forwarding and POP/IMAP tab, or if you use Google Apps, you might have a Forwarding tab instead.
In the "Forwarding" section, select the Disable forwarding radio button.
Click the first drop-down menu in the "Forwarding" section and check for any forwards created by filtering.