how do i leave?

[StephenG]

In all seriousness, any good boss/co-worker/training partner/father figure
knows that you have to do what's best for you. If he can't understand that
then he's probably not as great as you imagine him.

[DesiCuellar]

tell him that you want to start learning bjj because you find it very interesting and thats it. Nobody needs a good REASON to increase their knowledge in the fighting arts.

[Mikeox34]

You have to address that issue too. Tell him hey I know Dounchey McDoucherson just left for X reason but i want you to understand that i am leaving for this reason. Don't avoid it you have to address so that he knows exactly where you stand. You may discover in the process here that where you stand and where he stands may be two different places that would be opening and possibly difficult to take seeing as it is someone you highly regard. On the other hand you may be blowing this up to be bigger than it already is and he is gonna be all cool with it. On the other other hand he may be reading this right now and planning your demise via ninja stars and blowguns. Watch your back brother.

+1 haha thanks guys for all your help

[Jason Hyatt]

I would keep the instructors feelings in mind.

"Accidentally" shit your pants while training. Then you just have
to explain to him that you were very embarrassed and can't come back.
60% of the time, it works everytime.

I laughed so hard I almost did. Brilliant. Do this. I was gonna say +1 to Cody's advice but I changed my mind. This is way better.