Can't you delete them with a middle click with the mouse scroll wheel or via the right-click context menu?

Start Firefox in Use Troubleshoot Mode in Firefox to check if one of the add-ons is causing the problem (switch to the DEFAULT theme: Tools > Add-ons > Appearance/Themes).

• Don't make any changes on the Safe mode start window.

See:

• Troubleshoot extensions, themes and hardware acceleration issues to solve common Firefox problems

Thanks for getting back to me. What I found was very simple. Open the tab and there will be an "x" in the upper right corner of the tab. Click the "x" and it asks if you would like to delete the tab.