If you sign out of the currently installed version of Lightroom 6, using the menu command Help->Sign Out, then you can re-install Lightroom 6 an infinite number of times.
Why do you need to re-install? Re-installing doesn't solve most problems.
I am just a beginner. Switch external drives, deleted/moved pics/ folders not using lightroom 6 and the story goes on. I have a recent second copy (on another mac) that I am I am doing well and no issues. But this first copy is giving me problems, compounded that I am not to bright on the computer.
I am moving all my pics into another drive. Erase the external drive and start again. I hope. If you have any suggestions I would really appreciated. Thanks for the reply
Reinstalling will not fix these issues. Reinstalling in this case is a waste of time.
If you are moving photos to another drive, you probably want to read Part 2 of this document: Adobe Lightroom - Find moved or missing files and folders .
Will read the article before deleting or moving. I agree with you. I suspect I will inherit the same issues that happened when I reinstalled the first time.
Thank you again.
Just want to say that after reading part 2 I was able to get LR6 back functioning.