How can I uninstall Opera browser from my computer?
It may occur some errors, so reinstall it again.
Maybe you have several Opera's. Go to the control panel, then to "add and remove programs" and try to remove it from there.
Try using some uninstaller tool. F example IobitUninstaller or Wise Uninstaller.
Try using Revo Uninstaller. Even if it can't uninstall the application normally, it will force it to uninstall by wiping out all traces of its presence from the system.
After that, try running AdwCleaner to make sure that there are no leftover rogue registry keys or toolbars in your system.