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I am aware of no method to do this without leaving obvious traces. ... Please let us know how your experiment turns out! John
I'm not expecting to fool anyone. I would describe a cover to which this was done as "with address label (removed)."
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I think you will find when you do remove the label, there will be a chemical stain beneath it that cannot be gotten rid of
Here are a couple of covers demonstrating that:

The staining is definitely noticeable ... in the image. But less so to the naked eye. In the top one, it is not noticeable "at a glance;" you have to look closely (and the naked eye will notice that a thin layer of a portion of the label still adheres to the cover--see postscript below).
It is what it is. I don't think there is any difference in "value" between a cover with an address label, and one in which the address label has been removed. Both lack the value attached to an unaddressed cover. Aesthetically, I find the labels distracting, and thus the cover is more appealing to me with the label removed.
Whenever I have an addressed cover in my collection, I'm always on the look out for an unaddressed version. But until then, the "address label (removed)" will do.
Basil
Postscript:
I'm not sure how much of what you see in the image is evidence of actual "chemical staining," and how much has to do with image characteristics. In the top cover, the "staining" appears darker at the right end of where the label was. But it is darker because there is a layer of label still stuck to the cover. So the "staining" may in part be related to traces of the label left behind, and where the traces are thicker, in the image it appears darker.