When you wish to remove your keycals follow this simple steps:

Step 1:

Turn off your computer.

Step 2: 

Lift the corner of the sticker with your fingernail or the edge of a credit card. Slowly unstick the sticker, while holding the key with a second hand, so you avoid removing the key from a keyboard as well. Don't use any sharp tool - you'll most likely scratch the keyboard surface.

Step 3:

Repeat it with other keys.