[Dimensio]

18 USC 475

I have not stated any intention to produce counterfeit tokens in the likeness of US currency.

USC 3559

This actually does address defacing US currency, but only if it is done "with intent to render such bank bill, draft, note, or other evidence of debt unfit to be reissued". Marking out the IGWT phrase does not render the bill unfit for reissue. A small swipe of a Sharpie (just one or two is required) does not reduce the life expectancy of the bill, nor does it make it any less obvious the denomination of the bill.

[Dataman]

Then you wouldn't mind if I alerted the Treasury to your admission, would you?