Missing partition in my iMac Fusion Drive - can't do school work!
Your Windows partition isn't missing after erasing it! You gained some unallocated disk space. 

To reinstall Windows with Boot Camp Assistant you have to restore the ~vanilla Fusion Drive state. You can try to resize the whole Core Storage stack with the command with: diskutil cs resizeStack lvUUID size. In your case that's: 

diskutil cs resizeStack 9449131B-67F8-4D97-82D6-F2BDEDB48B6C 1022g


If you get an error "... not enough space ..." choose a slightly smaller size like 1021500m or 1021g.

After poking around with Disk Utility or the Windows Disk Management tool (e.g. trying to remove/resize a Boot Camp partition with Disk Utility) the resizeStack command often fails with a cryptic -8xxxx error message because some internal CoreStorage structures are corrupted. Your OS X volume usually isn't affected though.

Then you have to either backup the OS X partition with Time Machine, rebuild a vanilla Fusion Drive and finally restore the TM backup or install OS X from scratch after rebuilding a vanilla Fusion Drive.

Then you can launch Boot Camp Assistant and install Windows 10 again.