Is it a good idea to retire a jack of all trades character, I mean they do everything and I only scratched the surface and I'm level 40. I just finished the main quest but there still is so much to do. What level would be a good level to retire the. Character and start a new one?

Whenever you feel like retiring the character. That's the only reason really for retiring a character. Just getting bored of him, or accomplishing everything you wanted to with the character.

I guess that probably doesn't help much though.

At level 66 with my first and jack of all trades character. It's getting tough to play him though. Retirement MIGHT be in his near future.

Just do what you want really. Most of my characters end up doing most of the things.

the only thing mine isn't doing is the college of winter hold

There are two reasons to retire a character: 1) They've achieved their goal in the game e.g. MQ,CW Guilds etc.

2) You're bored playing them.

Only retire him if you are sick of playing him and want to start a new character! Some people do everything with one character, and some like to split up the quests/factions between different characters. You can bump up the difficulty if he starts to get too overpowered, or use a different skill if he gets a bit boring. Just play him until you are not having fun with him any more.

Do what everyone here said, just go with your gut. Play him til you get bored or wanna start fresh with a new one.