Wait for your return to be accepted by the state. If it is accepted, you can log back in and should be able to print a clean copy without the watermark.
There are two reasons for the watermark. In some cases, a state has approved turbotax for electronic filing but has not yet approved it for paper filing. In other cases, your return will be marked "do not file" if you try to print before your return is actually accepted by the state. This is so that, if you have to make changes to fix any errors, you don't get a clean copy that doesn't match the final filed version. Once your return is accepted the watermark should be removed.
