The best way to quickly and safely remove a sticker is to use acid-free primers. The most common brands are Bluesky, ruNail, Nayada. You have to slather the bulging edges of the sticker with a brush lightly soaked in the primer, then carefully remove with an orange stick or a fluffy stick.
Also you should pay attention on the end of the nail plate and remove the residue of the sticker to avoid damages. This can be done by using a small-sized nail file or bafic
The apply a bit primer on the nail plate by the brush. Dry in the lamp for 10 sec. At the end apply base coat on the sticker.