Dear manager,
Thank you so much for discussing my work situation with A and B. Four days WFH in a week, indeed, is a good offer. I wish this offer have had provided before I decided to move on. I have already accepted the offer from XXX, with regrt, I would like to resign my position in XXX. My last day is XXX.
Sincerely Yours,
IIyyy
这件事儿你已经赢了,就宽宏大量一点儿,给你的管理和A部门的领导留个好印象。山不转水转,没必要烧桥。