The Terminal app icon in the Dock is not cause for concern. If Terminal is still running, as indicated by a small dot below the icon, you can simply click the icon and then click Terminal > Quit Terminal from the menu bar.
I'm wondering what was it about the telephone support that made you suspect it was a scam?
If you initiated the call to Epson using a telephone number published on their website or in their printer documentation, then it was likely legit assistance.
Of course, if the call came to you out of the blue or you called a phone number that popped up on your screen with a message suggesting your Mac had a problem, well... that would be suspect.
You might find this light reading useful moving forward.
• Effective Defenses Against Malware - Apple Community
• Avoid phishing emails, fake 'virus' alerts…and other scams - Apple Support