Ways to help your child stop thumb sucking and pacifiers:
Do not punish or tease them. Instead, reward good behavior with praise. Stressful events can cause a child to suck longer because it can be calming/soothing for them. Do not put pressure on the child creating more stress.
Allow your child to keep a sticker/star chart to track their progress, give rewards for going a whole day or week without sucking their thumb/pacifier, and gently remind them when you see them starting to give in.
Sit down with your child and make a list of "big kid" activities they want to be allowed to do and "little kid" activities they need to stop. Make their "big kid" activities contingent upon them stopping their "little kid" activities.
Try putting a bandaid over the finger they suck to remind them when they start to put it in their mouth. Explain to them what this is for when you put it on.
If their teeth are becoming affected you can talk to your dentist about getting a piece that prevents them from putting pressure on thier teeth.