I went throught the leash biting too when they were
pups. Not as bad as Nebo.

I agree, with DoggiesAreBest. (take away and keep out of reach)
I taught Sheba/Rocky as pups to calm down and sit, before I put their leash on them.
If they bit at the leash or started jumping etc.,
I would say NO, remove leash from mouth,
and just wait until they sat and calmed down.
Than we we would go for our walk.
Didn't take to long for them to catch on, that
no sitting no walkie.

These puppy stories are bringing up memories.
Wait till Nebo started digging and chewing up your
yard. lol