If you're taking the PC for service, they should be able to handle your virus issue.
Once that's done if you want to bypass the Arc launcher and just start STO without it, that's easy enough. It doesn't need to be running to start the game at all. If you ever get any bonuses/freebies from Arc that apply in-game though, you will need to start the game from the launcher one time in order to claim them (for example: the Khan off-duty costume).
The launcher is an unstable resources hog that (best I can tell) has several memory addressing conflicts with the STO client, plus it's an always-on Internet app so it's using up some of your bandwidth too. It used to crash the game on me all the time so I always bypass it. Here's how:
Look for the folder named "Star Trek Online_en" which should be inside your "Program Files (x86)\Arc" folder. You should see "Star Trek Online.exe" in there, so just right-drag a shortcut from that to your desktop, or right-click it and you can pin to either the Windows start menu or the taskbar.
At that point you can either ignore or delete your original Arc shortcut, and just use your new one to start the game without the launcher fighting with STO for system resources.