How can I change my dependents

You can edit that in the "Personal Info" section of your return. 

You can delete their information, or go through the interview questions if you think you might claim them next year. 

To be claimed as a qualifying child, they need to meet the following requirements: 

"Are they related to you? The child can be your son, daughter, stepchild, eligible foster child, brother, sister, half brother, half sister, stepbrother, stepsister, adopted child or an offspring of any of them.

Do they meet the age requirement? Your child must be under age 19 or, if a full-time student, under age 24. There is no age limit if your child is permanently and totally disabled.

Do they live with you? Your child must live with you for more than half the year, but several exceptions apply.

Do you financially support them? Your child may have a job, but that job cannot provide more than half of her support.

Are you the only person claiming them? This requirement commonly applies to children of divorced parents. Here you must use the “tie breaker rules,” which are found in IRS Publication 501. These rules establish income, parentage and residency requirements for claiming a child"

The program also asks about Form 8332, in case you swap years with the other parent. 

TurboTax information about claiming dependents