select the Print & Scan preference pane.
This will show you all the printers that are installed on your iMac.
Select the Epson 740 in the left hand column and then hit the - (minus sign) at the bottom of that column.
The Epson will be deleted.
Note: You may have to unlock the pane using the padlock, and your password, at the bottom of the Pane.
My Epson 740 Color Stylus printer up and died after many years. I bought a basic Brother b & w printer. Now I'd like to uninstall the Epson, which is gone but whose icon still appears. I have an iMac OS 10.5.8. Can anyone advise me? Golditoo