Error removing Windows partition with Boot Camp Assistant

[Sirolway]

As I'd hoped, my wife never uses the Windows partition I set up for her on her 13" MBA so I want to remove it & reclaim the space for the main OS X partition.

I tried removing the Windows partition using Boot Camp Assistant but got an error at the end of the process (possibly because OS X partition has FileVault?). Now Boot Camp shows a 20GB partition (the Windows partition is actually 128GB) & I can 'drag the slider' to resize it larger, but there's now nothing about removing it.

Is there a way to remove the Windows partition, add the space to OS X partition without having to backup & restore all the data on the OS X partition?

Any help much appreciated ...

 

[Sirolway]

OK all fixed - just posting what I did for completeness ...

Disk Utility > Repair disk & it found errors which required a restart into the Recovery partition. Did that, then ran Disk Utility > Repair from the Recovery partition. Repaired successfully.
While I was there, clicked on the volume in Disk Utility, then the Partition tab, then dragged the size of the partition to fill the disk. Applied & it worked fine this time.

Restarted into the main (non-Recovery) partition & all is well - volume is now up to 256GB

All good - happy!