You cannot move or resize a mounted partition. The root partition you are booting your OS from is always mounted and cannot be unmounted, except by changing into another operating system.
As for the changing from dual boot to single boot to Windows:
An easy but not best way is to delete the Linux partitions in Windows, then restart Windows and shut it down forcibly during the boot process. Then it should start into a recovery menu, where you select that you want your “Startup behaviour” fixed.
However, I don’t remember if the same procedure works with Windows 7. It works for Windows 10, though.
Basically, all you need to do is writing Windows’ MBR into the HDD, again, so Windows can boot from it properly.