Trying to respec from Titan to something else but can't - level 75 - please help

Is this even possible. I'm level 75 and I'm getting ROLLED by level 68 and 69 monsters in the atlas map. I've decided to follow a guide and attempt to re-roll to a new spec, but I can't click the altar after completing sekhemas trial. It's like dead, doesn't even have an icon over it to click.

So is this possible or am I doing something wrong? I just want to proceed through the game but I'm getting my arse kicked.