Before removing any of those partitions please make sure you will not need them. It is quite irritating that your first partition contains a linux filesystem, while it should be fat32. Please before deleting save the content to some external disk - just to be sure.
Please don't just tell us where you are stumbling, please give the complete error message. Just two guesses: Is there a directory /home/user/bin at all? Make /home/user/bin/fdisk executable.