Praise be to Allah.
It is not permissible for the muhrim (pilgrim in ihram) to use perfume on his body or clothing, because of the hadith of Ibn 'Abbas (may Allah be pleased with him) according to which a man’s camel threw him and broke his neck when we were with the Prophet (blessings and peace of Allah be upon him) and he was in ihram. The Prophet (blessings and peace of Allah be upon him) said: “Wash him with water and lote leaves, and shroud him in his two garments , but do not put any perfume on him or cover his head, for Allah will raise him on the Day of Resurrection reciting the Talbiyah.” (Narrated by al-Bukhari (1267) and Muslim (1206)
Ibn Qudamah (may Allah have mercy on him) said: “The scholars are unanimously agreed that the pilgrim in ihram is forbidden to use perfume .” (Al-Mughni, 3/147)
The perfume that is forbidden to the pilgrim in ihram includes scented antiperspirant.
But if a person did that out of forgetfulness or ignorance , he does not have to do anything, because Allah, may He be exalted, says (interpretation of the meaning):
“Our Lord, take us not to task if we forget and lapse into error inadvertently” [al-Baqarah 2:186]
“And there is no sin on you if you make a mistake therein, except in regard to what your hearts deliberately intend. And Allah is Ever Oft-Forgiving, Most Merciful” [al-Ahzab 33:5].
And Allah knows best.