How to hide or remove Opera icon from the notification area or system tray in taskbar

You'll see an red Opera icon at bottom right in taskbar after launching Opera
In order to hide that Opera icon, add the parameter -notrayicon to opera.exe

For example, you can edit the link of Opera in desktop, add a blank space and -notrayicon to the end of opera.exe, like this: F:\Opera\opera.exe -notrayicon