CFOG's PIP, December 1987, Volume 6 No. 2, Whole No. 62, page 6

Removing Labels from Diskettes

Question:
How does one remove labels from a diskette? Is there a liquid that can be used that won't harm the diskette?

Answer:
Use peelable labels. I know there's a trade-off here, too. The easier it is to remove the label when you want to remove it the more likely it will come off when you don't want it to, usually when the disk is inside the drive and you're tugging at it to get it out and it doesn't want to come out.

Sometimes the label is on the diskette when you get it, adhering tightly. You can get some of it off by peeling with your fingernail, but there's a bit of it left, and lots of sticky adhesive. The problem isn't just diskettes. Some stores use the same kind of adhesive labels so 'label switchers' can't do their dirty deeds. We honest consumers pay the price: adhesive residue all over the flashlight, clipboard, or whatever.

The only solution I've found is floor adhesive remover. It's a smelly potion, and you should be sure to use it with adequate ventilation, but it does the job. It won't harm metals and most plastics that I've tried it on, including diskette jackets. Get it at your hardware store or any store that sells floor tile.