"Can I remove the on board display and use the Newhaven display with this development board?"
What development board? Provide context, your post is far too vague and non-specific.
https://community.st.com/s/question/0D50X0000BfuZ3iSQE/stm32f746gdisco-question
You will need to do the due-diligence on this. Review the circuits and signalling expectations.
If you can't make these determinations from available documentation, the answer is probably No, and you'll likely need to do the experiment and work up the code to come to a definitive answer. Or pay going rates for someone else to do the work.
