Hi I'm new here. So I'm sorry if this is daft question!

I've finally fumbled around and manged to create my first few maps in kmz format.
I was wondering is there some way I could have several maps on my Oregon 450 and select which one I require at a time and disable the ones I don't want to use?
The problem I have is that the gps comes up with a warning about to many map tiles when I turn it on?

Thank you in advance for any replies.

MudSlug