Yes put it in writing and keep an extra copy for yourself. Just thank them for the opportunity but you’re moving on and when your last day will be.

I just stood in front of my manager and told her it was a good chapter in my life, but I felt like it needed to end. And also told her I felt like working under the siren was borderline mental abuse. Which she completely understood.

Ultimately I feel like it's what you feel most comfortable with I recently did mine and I did it in person sat down with both of my managers and told them when my last day was. I feel like from a professional standpoint having it written is good but again imo it's what you feel most comfortable with.

I just put it in an envelope and handed it to them in person

Just give your manager a letter saying “my last day is xxx.

I only work one day a week, and never see my manager. She's also brand new and came just after my availability changed so we don't even really know each other but moving in from the company has been a long time coming. How should I go about giving her a notice?