I'd recommend keeping him seeing as you've come this far, and anyhow, I find it's often nice to switch to a pre-searing char once in a while, it's a nice change-up from thhe rest of the game.
However, if you really only wanted the titles for rewards in GW2, then the answer is yes, it's a complete waste of time, but that's how GW works really, everything is for vanities sake. I'm not an expert on the title myself, so I can't say how much longer you have to get to level 20, but I assume it's still a hell of a long time to go. If you are looking for improving HoM rewards, just go through all the other stuff first until your happy with your HoM, then if you feel like it, you can dedicate yourself to LDoA a bit more.
So overall, I'd definitely keep him, just in case
