There is a way, easy one too. On client, just set yourself on DND mode and pop you are offline. Make sure (if you use) that on imvu go? (mobile app/m.www) website is also set for "show as offline" otherwise, it will keep over-riding you on/offline now and then.
quite easy.. Oh oh and member, that if you check your own status, it will always say online. But ask a friend to look, if you are online or not. They should be able to tell
There is like 1-2 minute update interval for it to set in. So wait a moment and check. I hope this helps.