If loss of blood can lower blood pressure, can high blood pressure people dobaye blood?

Blood pressure. Patients with high blood pressure can physiologically donate blood. Often they will not be allowed to donate because they may be on anti hypertensive and other drugs. Gettting a transfusion which contains hypotension directed drugs could be a problem for some people.
The pressure returns. An otherwise healthy person with mild high blood pressure, or with moderate high blood pressure under control, should be able to donate blood as long as he doesn't have problems like anemia, hepatitis, hiv, recent travel to malaria countries, etc... After donating blood, a person's blood pressure can be lower but usually just for a brief time. The blood pressure goes back to where it was before.