How can I issue the phone manager?

I had to block a contact on my mobile (Huawei P10). I've blacklisted it and blocked it on WhatsApp. But I always get messages from the phone manager that a blocked contact sent me a message. (See picture) I'm pretty sure this news is coming through WhatsApp. Now my question. Can I cancel these notifications somehow?

I thank you in advance for your answers

If you drag the notification to the left (or right), but only so far as the gear comes, you can turn off notifications for this app

Either as VampirGirlLelo said, or hold down the message and press the blue button.
But remember that not only the message of the blocked contact is no longer displayed, but in general by the phone manager.