Just removed a long-present "Best Wishes" from this Paul Mitchell signed photo. I'm not sure how long the signature has been on there, but I've had the collection this came out of for at least a year, and don't know how long before I purchased it the previous owner got it signed.
As shown below, the original signature was in blue sharpie. I covered over "Best" with blue dry erase marker, wiped it away, took another scan to show in-progress, then removed "Wishes" as well. No residue, and no indications in reflected light that the "Best Wishes" was ever there.
This was done on a modern glossy, matte-finish photo. I did test it on a couple of other materials as well, including a semi-gloss card stock, and photo paper like you would run through your printer, and in both cases the dry erase failed to wipe off on its own, let alone take any sharpie with it. So I would caution you to use this method on full-gloss surfaces only, and test it before you risk anything permanent. Also, it probably goes without saying, but be sure to wipe AWAY from whatever writing you are trying to preserve.
