cut the majority of the yellow off without taking off the whole leaf..the plant needs them during the final stages of budding after you stop giving nutes
It won't get better on its own. But good luck with your grow.
Google marijuana magnesium deficiency and look at the pictures that come up. Then google the same with nitrogen deficiency...that should give you your answer.
Except for sometimes when cloning, you should never need to trim leaves. All this does is leave an open wound. It's not going to hurt that plant at all if a leaf has a brown spot on it. Much of that yellow will go back to green when the plant gets proper nutrients. As for adding magnesium, that's what Cal mag is for.