The Blue Calendar is the default calendar provided by your calendar service. You can’t rename it.
The Green birthdays calendar is a calendar generated by your calendar provider from your contact’s birthdays. If the server says it is there, eM Client will display it. You will need to ask the calendar provider how to disable it. When that is done, right-click on the Calendar folder for that account and choose Properties > Repair > Repair. That will resync the calendar from the server and display only those folders the server says are there.
The Yellow folder names are supplied by the Exchange server. You can’t rename them.
Ok thanks for the info ,
Should I create a feature request?
seems something achievable to me if the provider name is used a sort of ID and the label is actual filled by a sort of alias.
Thanks in advance