I'm telling you, use wind oil, gently rub it, and try it. By the way, don't be too stingy. Touch and scratch the cover of the book.

Is the landlord talking about bookmarks in the book? After soaking gauze or absorbent paper in water, cover it on the adhesive and let it soak slowly. To a certain extent (you need to judge for yourself), it should be all right to peel it gently or rub it with your hands, or peel it off as a whole, or peel it off one by one. This is what I do with self-adhesive bookmarks in many books. I hope yours can be cleaned, too

Generally, if the cover is pasted with plastic, the adhesive can be carefully torn off. If it is difficult to tear, it will be easily removed by blowing it with a hair dryer and hot air. Rubber can be used in small areas.