Do I need to detail a person if it is not claiming as dependent?

No.

If you do not claim a person as your dependent, you do not need to enter their details in your tax return.

Maybe.  Why are you not claiming them?

In cases of parents who are divorced or separated, only the parent who has custody more than half the nights of the year can automatically claim the child as a dependent.  The custodial parent can allow the non-custodial parent to claim the child as a dependent only by giving the non-custodial parent a form 8332.  Only the custodial parent can use the child to qualify for EIC, head of household, or the dependent care credit, those benefits can't be waived, shared or transferred.  If you are the custodial parent and are releasing the dependent claim with form 8332, you should still list your child and answer the questions, so you can get those other tax benefits if you are otherwise eligible. 

If you live together unmarried with the other parent, then either parent can claim the child, form 8332 is not needed, and you can't split the tax benefits of a dependent.  The parent who claims the child claims everything.  In this situation, it is a good idea for the parent who is not claiming the child to leave the child off their tax return entirely.

If you have a child who has simply outgrown being claimed as a dependent, you can certainly delete their name from future tax returns.

If the situation is something else, you may want to post more details to get clarification.