Upgrade from photoshop 2010 to 2018

Yves,

It's not necessary.

The usual advice is to desinstall only after testing the new version and checking that you don't miss any feature missing or changed in the new version.

If you desinstall to save space, it would be prudent to  'deactivate' the license from the Help menu; that' will keep the license available for another computer.

If you have a current catalog on your computer, you'll get a prompt to 'udpdate' the catalog. A new catalog is created from the data of the old one, which is still available with the old organizer.

What features from previous versions are not available in Adobe Photoshop Elements 12?