The guy wants to anonymize the magazines, if he is concerned about it I assume he has a reason (worried about identity theft?) , and dismissing it outright and offering stupid obvious suggestions like sharpies doesn't help anyone, it just makes you look pompous.
To OP - if it is printed directly on the cover and not a label you can remove, then your only real option Either:
a) Cut out the address with scissors. Whoever you are donating them to hopefully should not mind that.
b) Use a more powerful compound like lacquer thinner and rubbing to try to dissolve the top shiny surface (and address) off the magazine. Doing would *probably* ruin the cover in that area anyway though, so you probably will still need to cut it out.