Once you're promoted, you can't be demoted except as punishment for failing missions. You can't be demoted even if you go a hundred years without accepting a mission, but for every year you don't, you'll lose an increasing number of Merit Points. You can choose not to accept missions and stay at 0 Merit Points if you want, and you'll still receive all the perks of your current rank.
There is one thing you'll lose out on in that event, though. As long as you're not at 0 Merit Points, you can request assistance from other members of the same rank by submitting missions yourself. You won't spend your own Merit Points to do it either. However, missions are expected to be created for serious matters. At the very least, it should be something on the order of requesting to trade for resources at a discount. If you submit for something trivial as a joke or something, your mission creation privileges can be revoked and you'll have to spend merit points to get them back."
