To remove the icon from your cmd+tab: open the preferences/settings for the application and under "Application Options" use the multi-select field from "Both" t

To remove the icon from your cmd+tab: open the preferences/settings for the application and under "Application Options" use the multi-select field from "Both" to "Only Menu Bar", then restart the app. The icon won't be in your dock or cmd+tab anymore, but lives in the menu bar :)