Disabling or deleting an existing restriction, a website for example, doesn't work and I can't enter the website. I have to delete whole configuration and create a new one from the beginning.
did you try rebooting the device?
Why should I reboot the device? There should be no need for rebooting device or deleting config. I mean if I turn it off (see the attached) It should allow the website. (i.e snapchat on the screenshot)
CENK ATASEVEN because rebooting device will clear your DNS cache in OS and browser
Once an address is blocked it takes ~5 minutes since you disable /delete /allow to take effect.
You don't need to go nuclear by deleting the configuration.