Depends if they were clear coated. In most cases, a plastic credit card or your fingernail will do. Then use Goo Gone to rub off the residual adhesive.
It might surprise you as being very easy. Take photos first, in case you want to find replacements later. You'll forget what they looked like.
imho.
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1959 Hilton Wrigley Connoisseur (my favorite!)
1963 Hetchins Mountain King
1971 Gitane Tour de France (original owner)
* 1971 Gitane Super Corsa (crashed)
* rebuilt as upright cruiser
1971 Gitane Super Corsa #2 (sweet replacement)
1980 Ritchey Road Touring (The Grail Bike)
1982 Tom Ritchey Everest
(replacing stolen 1981 TR Everest custom)
1982 Tom Ritchey McKinley (touring pickup truck)
1985 ALAN Record (Glued & Screwed. A gift.)