RE: Hide 'Related' tab from the Case for interactive Experience form.
Hi Apurva,
You could hide it using Javascript.
This is the code for Javascript:
var hide = true;
var interval = null;
function hideRelatedTab(){
interval = setInterval(function () {
var element = parent.document.getElementById("rel4");
if (element !== null && hide === true) {
hide = false;
element.style.display = "none";
clearInterval(interval);
}
}, 1000);
}
You need to set it to the onLoad event of the Case for interactive Experience form.

In this case, the 'Related' tab will be hidden each time the user opens the form.

This blog is about how to set up Javascript for a form:
[View:https://www.tutorialspoint.com/microsoft_crm/microsoft_crm_jscript_web_resources.htm:320:50