My friend dropped Ext 1 maths today (Not quite the same but you know). She is smart and did accelerated maths last year, she used to like maths and not anymore. She is good at it but it would require some work. She found it hard and confusing and too much work and decided that she doesn't really like it, so she dropped it. She had more units than neccesary anyway.
I'm not entirely sure why i'm telling you this, but i just am.
I suggest you try and struggle through until the end of the term. Review your results and see how you've done. If it is 'breaking you soul' as i call it (which is exactly what English is doing to me), then don't put yourself through all the pain and effort. I think it's a good idea that you started in Advanced, better to try and drop down.
My other friend was in the highest maths class last year and did... average. This year she elected for general maths (she could have done advanced, but she doesn't like maths and would have had to work a bit), now she is top of her class (something rare to her) and sometimes actually likes turning up to maths, which is very uncharacteristic. Look if you don't want to do it, and you don't think it will be important to your uni course (which is very unlikely) then i say hang on a bit, and then just do what you feel.
Do you really want to struggle and take up half your time with maths? Do you really want to be bored in general and know you could do better? Try asking your teacher what they think.
I hope that helped, however i have a feeling it didn't.