Ive tried to look in the extensions and other folders to find it to delete it but have had no luck doing so.
It will not bear an obvious name.
Since you already know how to inspect folders and extensions you can use the following technique to identify the culprits:
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Please restart your Mac in "Safe Mode": Use safe mode to isolate issues with your Mac. The message should not appear, but will reappear after restarting your Mac normally.
While in Safe Mode please examine the contents of the following three separate folders:
~/Library/LaunchAgents
/Library/LaunchDaemons
/Library/LaunchAgents
To navigate to the first one, copy that entire line and paste it in the Finder's Go menu > Go to Folder... field.
Make it look like this:

... and click the Go button. A Finder window will open. Make that window large enough to capture all its contents, so that names of all the files it contains are readable. Take a screenshot showing all that folder's contents. The screenshot will be deposited on your Mac's Desktop. Give that screenshot a name so that you can distinguish it from others you're about to take.
Repeat the above for the other two folders. In the end you will have captured three separate and distinct screenshots. Then, please restart your Mac normally, return to this site and post all three of them in a reply.
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To learn how to take a screenshot and include it in a reply to this Discussion, please read the Appendix in the following User Tip: Writing an effective Apple Support Communities question. Screenshots (Mac) starts about two-thirds of the way down.