Sorry to hear this. Have you identified his triggers (bored, frustrated,
HALT - Hungry, Angry, Lonely, Tired, etc)? Might there be 2e issues?
Also, remember that there is a distinction between
temper tantrums and
meltdowns (which are
caused by being overwhelmed). The causes are different, and the approaches to resolving them also differ.
... normal just once a week and just for 45 minutes.
Be aware the weekend enrichment program may differ considerably from the regular classes. Meanwhile, if you find that keeping him mentally occupied is the key, there are many resources for afterchooling at home, including online resources, many of which are free.
In the public school He is attending, his teacher took everything he played from his hand. I realized that He is playing with his teeth now.All the time He is putting his hands in his mouth. This week I have a meeting with them. we will see what will happen

.
You may wish to
prepare for the meeting by reading up on characteristics of giftedness, triggers, 2e, etc. This may help you gauge what the teacher has observed, and may also help you request appropriate next steps (testing, differentiation, cluster grouping with others of similar readiness and ability, etc)
This may be obvious, but have you talked with your son about his behavior... is it something which he is able to control... or which he may be coached to be able to control? While many children may fidget, then naturally calm down when they are mentally occupied, this is different than knowing that throwing a tantrum will manipulate adults into giving them whatever they demand.