Technically, yes. You can open Task Manager and end the vgc.exe process. However, doing so will immediately prevent Valorant from launching online matches. You will not receive a ban, but the game will tell you that Vanguard is inactive. The only way to restart vgc.exe properly is to reboot your entire computer.
Here are the most common errors related to vgc.exe and how to resolve them. vgc.exe valorant