There is no reason to do so. The two versions can co-exist quite nicely. PrE 12 will install into a different folder structure, from your PrE 10 installation.
Many users keep the older version(s) installed, until they have learned the newer version - there are some significant changes between PrE 10 & PrE 12. Then, when they are fully up to speed with the newer, might consider Uninstalling the previous. A few users keep each older version, because one might do something better, or for testing purposes in the forums. I have a few older versions, and at least two users have about everything, going back to about PrE 4.