This pop-up always shows every time I log onto my iMac. What is it and how do I make it stop?

Michael, the org.chromium.chromoting.me2me.sh is a shell script that is part of the Chrome Remote Desktop software. If you never intended to enable that software, then I suggest you remove it: from within Chrome, go to Plug-Ins, or go to chrome://apps, and check the corresponding "Disable" box (you may need to log out and back in). Doing this will remove it from your login sequence.

On the other hand, if you did intend to use Chrome Remote Desktop, than when that dialog box appears, click on the "Open System Preferences" button, and check the box next to the org.chromium.chromoting.me2me.sh and it won't bug you again.

See this article Change Privacy preferences on Mac - Apple Support

An example , in security and privacy open the padlock by authenticating Admin name and password check mark the app , tap it to get highlighted , and click on subtract sign to remove it .

Its gone .

Did you installed chrome browser in Mac , in finder - applications can you see it .

Use EtreCheck

And post back the results .

Check system preferences > users & groups > [your username] > login items.