How to hide .sapMPageHeader?

Hello, I am trying to hide .sapMPageHeader because I have shell that displays the header so I don't need a .sapMPageHeader. I've tried hiding this with CSS through this:

.sapMPageHeader{
display: none;
}

This works except I am not able to directly do this cause "Override of common (sap.ca / sap.m) css classes are not allowed sapui5" .