How to uninstall Ubuntu from a dual system?

To remove the Ubuntu dual system, you need to follow the steps below:

1. Firstly, backup all important files and data. Deleting Ubuntu will remove all data related to Ubuntu on the hard drive, so make sure you have backed up all important files to another storage device.
2. Remove Ubuntu boot from Windows operating system. Access “Control Panel”, click on “System and Security”, then select “Administrative Tools” and choose “Computer Management”. Click on “Disk Management” on the left side, right-click on the Ubuntu partition, and select “Delete Volume”. This will remove the Ubuntu boot and partition.
3. Repair Windows boot. In Windows, press the Win+X key, select “Command Prompt (Administrator)”. Enter the following commands and press Enter to run:
   bootrec /fixmbr
   bootrec /fixboot
   bootrec /rebuildbcd
4. Delete the Ubuntu partition. Go to “Control Panel”, click on “System and Security”, then select “Administrative Tools”, and then select “Computer Management”. Click on the left side on “Disk Management”, find the Ubuntu partition, right-click and select “Delete Volume”.
5. Expand the Windows partition. In Windows, open “Control Panel”, click on “System and Security”, then select “Administrative Tools”, and then choose “Computer Management”. Click on “Disk Management” on the left, right-click on the Windows partition, and select “Extend Volume”. Follow the prompts to expand the Windows partition to the entire hard drive space.
6. Please restart the computer. After rebooting, you will only be able to see the Windows operating system.

Please be aware that removing Ubuntu dual-boot system may lead to data loss or other issues, so make sure to back up your important files and data before following the steps above.