I have photoshop elements 12 & premiere elements 12 installed.
I purchased the elements & premiere 13 upgrade edition and installed.
I believed the upgrade version would install over the existing version 12 but its installed alongside version 12 instead so I know have version 12 & 13 installed.
Can I uninstall version 12 without ' upsetting the version 13 upgrade and if so how come?
All versions of Elements (Photoshop and Premiere) are, as you have discovered, completely independent programs
The "upgrade" is only a reduced price from Adobe, not a program that installs "over" a previous version
As far as I know, you may deactivate and un-install your previous versions
As John has pointed out Premiere Elements 12 and 13 are standalone products.
If you want to get rid of 12 permanently from your computer, please deactivate it first from within an opened project using Help Menu/Sign Out.
Sign Out is Premiere Elements 12's Deactivate. Deactivate and uninstall are not the same thing. So, as I said, first the deactivate, close out of the
program, and then the uninstall the usual Control Panel route.
To do a clean job of it, you may want to consider a run through of the free ccleaner program to get rid of any leftovers from incomplete installs and uninstalls.
Use the Windows or Mac ccleaner in accord with your computer operating system.
Any questions or need clarification, please do not hesitate to ask.
Add On....You may want to leave Premiere Elements 12 as is until you are settled in with 13. There have been several features discontinued in 13.