We don't know how long your son has been attending school. You do need to realize, however, that few young children feel at home immediately in a school setting. It's always a good idea to give them a few weeks to adjust. If your child still doesn't feel comfortable by then, you should consider taking him out of school.
Before making a decision, be sure to talk to your son's teacher. You may discover that he settles down fairly quickly after you leave and participates happily in the activities. If this is the case, you both need to work on handling separation better to avoid the daily trauma.
Your child's teacher should have solid suggestions, as she has probably encountered this situation many times. Sometimes, it helps for children to be taken to school by another family member or with another child in the same class. You might also stay with him for a while and help him get started on an activity before saying goodbye.
If your child truly does not seem ready for school at this time, it's best to withdraw him from the program. Remember, young children change very rapidly, so he may be eager to attend school in just a few months. You can help him on the road to independence by giving him the opportunity to make short visits to the homes of relatives and friends with young children. Be sure to stay with him for the first visits until he becomes comfortable.
Learn more: Connecting with Your Caregiver.