Could you please give more details of the problem when you say "PC want to access PE 7.0 even though it has been uninstalled."
Usually uninstalling a product should handle the problem of purging that product from the machines. Some files specific to that version are still left, but that does not create problem for the installation of the later version of the product. Even then if you want to manually clean those files, then after unstallation of say PRE7, go to following locations and delete those.
- C:\ProgramData\adobe\Premiere Elements\7.0
- C:\Users\<username>\AppData\Roaming\Adobe\Premiere Elements\7.0
And same you can do for PRE11.