As salam alaykum, sometime I used to pray without wudu .does this act takes me out of Islam ? I never had intention to mock islam and it's ruling .what should I do now ?

All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.

It is obligatory for you, dear sister, to repent to Allah the Almighty for praying without performing ablution knowingly and intentionally, because this is a forbidden act. Thus, whoever deliberately prays without ablution, with the presence of water and the ability to use it, has committed one of the greatest major sins – we ask Allah to protect us from this.
Rather, some scholars – who are the Hanafi and some of the Maliki scholars – are even of the view that those who deliberately did this act are disbelievers, because this act indicates his mockery and disregard for the Sharia. However, some other scholars are of the view that he does not disbelieve.

Al-Nawawi said in Al-Majmoo’ regarding one who prays without ablution: “If he is aware of the ritual impurity and the prohibition of praying with minor impurity, then he has committed a great sin, we do not consider him as a disbeliever unless he considers it lawful. Moreover, Abu Hanifa said that he is considered a disbeliever for his mockery; our evidence is that it is a sin, so it resembled Zina (fornication or adultery) and the like.” [End of quote]

Sheikh Al-Islam Ibn Taymiyyah said: “A Muslim does not pray to other than the direction of the Qiblah, and whoever did that deserves dispraise and punishment.” [End of quote]

You also have to make up those prayers that you performed without ablution.

Allah knows best.