My charging sticker came off really easy. I removed it on a really warm day. Pulled one corner of it up with my thumbnail and then slowly pulled it up to the other side.
It came off completely with no residue.
After that, I disabled the charging feature as I’m mostly on CarPlay through the USB and my phone gets charged that way.
I guess I got lucky too. Just like JS SAYN, pulled up one corner with my fingernail and then slowly pulled the entire label off without leaving any residue on the charging mat! But, mine remains enabled to place my S8 on it for alittle juice now and then.