Someone tried to take the stickers off my HCH a few months ago so an eighth of my passenger side sticker is slightly peeled back. The stickers apparently disintegrate as you try to pull them off.

This is what I've done in the past for regular bumper stickers:

1. Use a hair dryer to heat up the sticker.
2. Carefully peel away the sticker while its warm.
3. Use a soapy water mixture or if its really strong adhesive, commercially available adhesive remover, to remove any remaining adhesive residue.