Even though I set "parametersAreaVisible" to false, the parameter area is still visible. A bit of tweaking.
Let me make a change request in the telerikReportViewer-18.3.24.1112.js file:
function showParametersAreaIfNecessary(params) {
parametersAreaNecessary = hasVisibleParameters(params) || !controller.isReportAutoRun();
showParametersArea(parametersAreaVisible && parametersAreaNecessary);
}