1. Follow the instructions here to seek a refund (and to cancel automatic renewal):
https://tinyurl.com/37veskdd
2. Disable Bullguard/Norton (if it's actually running now) and then uninstall it:
https://www.techsupportall.com/how-to-uninstall-bullguard-antivirus-completely-remove-it-manually/
3. Check that Windows Security has automatically replaced Bullguard/Norton (as it should have done):
Go to Settings > Update & Security > Windows Security > Open Windows Security
(If, for some reason, Windows Security is shown as disabled, click to switch it on).
4. Sit back and relax. You don't need Bullguard. You don't need Norton. You don't need AVG. You don't need Avast. You don't need any other third-party software. Windows Security is all you really need.