usability – How best to guide your users when you move a critical feature?

Users of my site start a journey with a single user via an entry point on the homepage. We have trained them to do that, but since it is not the universal model and it has financial implications, we want to move away from it.

I'm afraid that by removing the current entry point, users will think this service is no longer available and will not abandon it. Some education is needed and hoped that someone could provide research or data on what works best.

I think that global messages and modals can be closed so easily and people would be blinded.