How is a guild mark removed? After failing to win, Yukino faces the anger of Sabertooth's Guild Master, Jiemma. Displeased by the failure of Team Sabertooth on the second day, Jiemma throws grapes at Yukino's head and forces her to strip, telling her to erase her guild mark,


How exactly does a person remove a guild mark? Is there a special magic for this?
We really don't know how the guild mark is removed, but Yukino do it with her own magic.
Sabertooth's Guild Master order her to remove it by her own magic and she do it.

We know that guild marks are given by stamping someone with the rubber seal like thingy. When Lucy entered the guild, Mira used this device on Lucy to give her the mark.


   In the battle Lucy vs. Flare, Flare tried to burn the guild mark. {So I think any magic can remove it}.
 Future Lucy didn't had a guild mark. {Maybe because the guild was destroyed and the guild mark also vanished or someone removed it from her}


This answer is only based on the anime :)