If they wanted you to be able to leave without a leave penalty, then they wouldn't have a leave penalty.

If you want to leave, you don't need the group to kick you. (That's not what "Kick" is for, anyway.) There's a built in "Leave" option already available. That's what you're supposed to be using. You're also supposed to get a 30 minute penalty every time you do that, because that penalty discourages people from doing this all the time.

If the reason you want to leave is because the group is consistently failing, then there's also the "vote abandon" feature. That lets you leave without penalty if the entire group is leaving. But it's only if the entire group is leaving, because in that case you're not abandoning anyone. If the rest of the group wants to keep trying, and it's just you that's leaving, then you deserve the penalty for leaving them short-handed.