The ability to successfully remove an unwanted label depends on the label, the adhesive and the material to which it is attached.

Labels are most easily removed where the tensile strength (stretchability) of the label is greater than that of the adhesive, and where the surface to which the label is attached is relatively firm and smooth. Sometimes they can peel right off, most times one has to take it slowly and carefully. Labels on fragile material are best left alone for fear of tearing or damaging the underlying material.

If the surface below the label is impervious (such as hard or soft plastic, coated paper or mylar), you can usually remove sticky or gummy traces from the surface with a small piece of paper towel moistened with a cleaning product called Simple Green. After use, be sure to wipe off the Simple Green, which is a chemical that may react over time, with a water-moistened paper towel.

To read the earlier E-Sylum articles, see:
ANSWERS: REMOVING PRICE STICKERS FROM BOOKS (www.coinbooks.org/esylum_v11n25a14.html)
NOTES FROM E-SYLUM READERS: NOVEMBER 1, 2015 : Removing Price Stickers From Books (www.coinbooks.org/esylum_v18n44a11.html)