Returning from Dual-boot to just Windows
There are two factors here:
- first, repair the MBR so that you can boot to Windows (it may be dangerous to start deleting partitions if you aren't sure that your boot-loader doesn't use them). This knowledge-base article covers some scenarios, but make sure you understand it before hacking around...
- second, use disk management in Windows to identify and remove the offending partitions
Be cautious. Most of these operations can (if done incorrectly) leave your system unbootable, and/or cause data loss. Perhaps backup any critical data first.