You can block contact numbers with your ColorOS 5.2 device. Check your ColorOS versio in [Settings] > [About phone].
Block feature helps you to prevent unwanted phone calls and messages from reaching you. You can also add numbers to Blacklist to block specific phone numbers, or add numbers to Whitelist to allow their calls to come through all the time.
Block the number on dial pad interface
Enter the dial pad interface and choose the number you want to block, then click SeeIf you want to unblock it, just click Remove From Blacklist. After this, you will not receive any calls and messages from that contact number, Add to Blacklist.