Ok, got your issue now. As you can't drop the column on which you have partitions, so you need to delete the partitions first. But I don't think you can remove all the partitions. So, I guess the best way is to drop the table by taking backup of data and recreate without that column and insert data again from the backup table. Thought about it alot, but not sure if there is any better way. Let me know if you find any different solution.
Ok, got your issue now. As you can't drop the column on which you have partitions, so you need to delete the partitions first. But I don't think you can remove all the partitions. So, I guess the best way is to drop the table by taking backup of data and recreate without that column and insert data again from the backup table. Thought about it alot, but not sure if there is any better way. Let me know if you find any different solution.