Lost Lightroom 6 after cancelling trial Lightroom CC

[pideja]

For many years, I have been using Lightroom 6 on my Windows 10 workstation. Yesterday, I decided to tryout the latest Lightroom as a trial. After having tried it for a few hours, I decided to cancel my subscription and revert to my stand-alone copy. Alas, it had been zapped! Why? How do I recover my now lost app.?

[dj_paige]

So install Lr 6 again. https://helpx.adobe.com/lightroom-classic/help/lightroom-6-end-of-support.html

And do yourself a favor and save this download installer file someplace where you can find it in the future if you need it, as it will not be available for download after a certain point in time.

[Rob_Cullen]

It gets complicated!

If you have the Adobe Creative Cloud Desktop App still resident on your system, then Lr6 will install as a subscription version with a 30-day trial.

Before you install the 6.14 version from the link by @dj_paige  I suggest you use the Cleaner Tool to wipe all vestiges of the Desktop App from your system CLEANER TOOL 

Then you may also strike 'Activation' problems that only a chat with Adobe staff will result in an 'Activation Reset'. (Adobe limits activations for Lr6 to two.)