How to remove Windows Operating system from Bootcamp?

Solution 1:

Apple helps:

Boot Camp: Remove Windows from your Mac

How you remove Windows from your Mac depends on whether you installed Windows on a disk that has multiple partitions or one that has a single partition.

Important: Back up all important data stored on your Windows partition.

If you installed Windows on a disk that has multiple partitions

1. Start up your Mac in OS X.
2. Quit all open apps and log out any other users.
3. Open Boot Camp Assistant, then click Continue.
4. Select “Remove Windows 7 or later version,” then click Continue.
5. Do one of the following:
   • If your Mac has a single internal disk, click Restore.
   • If your Mac has multiple internal disks, select the Windows disk, select “Restore disk to a single OS X partition,” then click Continue.

If you installed Windows on a disk that has a single partition

1. Start up your Mac in OS X.
2. Open Disk Utility, located in the Other folder in Launchpad.
3. Select the Windows disk, click Erase, choose the Mac OS Extended (Journaled) >format, then click the Erase button.

Solution 2:

• Launch the Boot Camp Assistant.
• Click the Continue button in the first screen.
• Select the Create or Remove a Windows Partition option in the next screen
• Click Continue again.
• Select the drive that has your Boot Camp partition, enable the Restore Disk to a Single Mac OS Partition option, and click Continue.
• You’ll be prompted for your administrator’s name and password.
• Click OK and Boot Camp Assistant will restore the disk to a single Mac OS partition.