Art; There is nothing hard about removing the self stick stamps of today. The same method used 10 years ago works just fine. Trim the unused stamps from the envelope with a pair of scissors and put it into a saucer of water overnight to soak. By morning the stamps will peel off the paper effortlessly. Put the stamps on a dish towell and let dry. (Sometimes I put them on top of the hot water heater to dry... takes 15-20 minutes). A glue stick is all that is needed to re-adhere.
My wife laughs at me when I trim unused stamps from envelopes almost daily ... some of them are $1 stamps ... while she cuts out 20-cents-off coupons from the newspaper advertisements.