My daughter is 8yrs old & her teeth on the bottom r not loose at all &the new ones are fully in. Is she too young to be put under to have them pulled?

No. If your 8 year old daughter has teeth that are indicated for removal, is healthy, and extremely anxious, having the procedure performed under sedation or general anesthesia by a qualified and trained person is not a contraindication. It may be less traumatic as well as sometimes safer if she is extremely anxious and/or combative.
Check with dentist. Check with your dentist, have the dentist take an x-ray to see how much root is left on the primary teeth. An orthodontic consultation may be advised as well. Usally, the permanent teeth come in after the roots on the primary teeth have resorbed and are loose. Sometimes, the permanent teeth come in in front of the baby teeth and need to be removed, this is normally done under local anaesthesia.
Pediatric Dentist. Have your daughter evaluated by a pediatric dentist. Her age should not be a factor for the anesthesia.
Delayed eruption. Not abnormal, some children will get their teeth earlier while others later. It is normal. When children's teeth come in later than average, it is called delayed tooth eruption. If concerned see a pedodontist, dentist for kids. Good luck.
No. Before anything drastic, have a dentist take a simple x-ray to see when the baby teeth will be falling out. About "putting out", baby teeth come out very easily (if it's even needed) many times not even needing any anesthesia, believe it or not!
Have them evaluated. Without seeing your daughter and without knowing what a current x-ray looks like of the lower right baby teeth look like in relation to the lower right adult teeth, it's difficult to answer that question. But 8 years old is not too young to have teeth extracted. Her health, medical condition & her tolerance for having dental procedures performed need to be assessed by a dentist to make that call.