Good evening Craig and welcome to the Events Calendar forum!
Thank you for your interest in our products.
We’ll be glad to answer your questions.
Do we need to remove the free plugin first and if we do will the calendar data be there after installing the PRO version or do we need to install the PRO version first and then remove the free version or do both versions have to be on the system ?
No, you do not need to remove the free plugin.
You will need to download the Pro add-on from your account and install it alongside the free plug-in.
Let me know if that helps.
Have a great day!
Geoff B.