I upgrade from Lightroom 3 to Lightroom 5. There was no problem. My pictures have been imported in Lightroom 5. But Lightroom 3 was not removed from my computer. How can I remove this old version in a good way ?
I use Mountain Lion on Mac.
I'm not a Mac user. But you remove Lightroom just like you would remove any other application from your system. If you purchased Lightroom 5 as an upgrade it probably depended on knowing the serial number of your Lightroom 3. I suggest that you store that Lightroom 3 serial number somewhere you'll remember because it will be needed if/when you decide to upgrade to a newer version of Lightroom.
And, just to clarify, there is no interdependence between your Lightroom 5 and Lightroom 3. They are separate, independent applications.