Based on user requirements, you may want to hide the related tab on a Dynamics 365 form. This is the tab to the right of the other tabs, and provides access to related entities:
To remove the related tab from a Dynamics 365 UCI form, do the following.
Open the form in Customizations:
Go to Form Properties:
Uncheck Show Navigation Items:
Save and Publish.
Now when we refresh the form, we see the Related tab is removed.