Sometimes, one needs to remove (not hide) all TinyMCE editors on the page to run a modified version of the global tinyMCE.init code again. This is the best way I’ve found to do it so far:

var i, t = tinyMCE.editors;
for (i in t){
    if (t.hasOwnProperty(i)){
        t[i].remove();
    }
}
// new tinyMCE.init code here

Additionally, you can “destrory” and “recreate” specific editors via:

tinyMCE.execCommand('mceRemoveControl', false, 'idOfElement');
tinyMCE.execCommand('mceAddControl', false, 'idOfElement');

If anyone knows a better way, post in the comments.