My employer just tried this on me when I handed in mine. “Give me a week or two to accept your resignation and then we will start the process.” I am not a confrontational person but I am direct. “No. You have no decision in accepting a resignation or not. You can acknowdlge my resignation letter and mine resigning but regardless it is happening in the time frame mentioned.”.
Words are power. Know your rights and defend the words because others will try to change them and take their power away. Employers do not accept your resignation because they have no choice in if you resign or not. All they can do is acknowledge it proffesional and discuss terms from them for you leaving.
No if you excuse me, I am going to brace this winter night and go celebrate my acknowledged resignation (strange how it didn't take 2 weeks for that to happen) with friends and whisky.