Honestly sometimes being a sensitive parent who cares about your child’s emotional wellbeing isn’t just compatible with telling them no, it requires that you do.
Or in plain English, kindergarteners don’t make parent decisions. Acknowledge her feelings about your choice to remove her, but be clear that the decision is already made and not up for debate.
I’d plan a fun first week of home kindergarten and talk about it a lot. Make a stack of favorite books to read together, go shopping for new crayons and paint, maybe even plan a field trip. At this age, distraction is still my favorite parenting technique.