Praise be to Allah
Whoever circumambulates the Ka‘bah in a state of janaabah, his tawaaf is invalid according to the majority of scholars.
It says in al-Mawsoo‘ah al-Fiqhiyyah (16/52) – under the heading: What it is haraam to do because of janaabah:
It is also haraam to do tawaaf (circumambulation of the Ka‘bah), whether it is obligatory or supererogatory, because it is akin to prayer, as the Prophet (blessings and peace of Allah be upon him) said: “Circumambulation around the Ka‘bah is prayer, except that Allah has made it permissible for you to talk during it.” The correct view is that its isnaad is mawqoof, ending with Ibn ‘Abbaas. Therefore tawaaf is not valid on the part of one who is junub. This is according to the Maalikis, Shaafa‘is and Hanbalis. But according to the Hanafis, tawaaf done by someone who is junub is valid, but he has to sacrifice a camel, because in their view being in a state of purity when doing tawaaf is not a condition of tawaaf; rather it is waajib (obligatory). And it is narrated from Ibn ‘Abbaas that he said: A camel must be sacrificed during Hajj in two cases: if one circumambulates the Ka‘bah whilst in a state of janaabah, and if he has intercourse with his wife after standing in ‘Arafah. End quote.
Shaykh Muhammad ibn ‘Uthaymeen (may Allah have mercy on him) was asked about someone who did tawaaf al-ifaadah when he was junub and he replied:
He has to repeat tawaaf al-ifaaah, because he did tawaaf when he was in a state of janaabah, and tawaaf is not valid if it is done when one is in a state of janaabah, because the one who is in a state of janaabah is not allowed to stay in the mosque, as Allah, may He be exalted, says (interpretation of the meaning): “Approach not As-Salat (the prayer) … nor when you are in a state of Janaba, (i.e. in a state of sexual impurity and have not yet taken a bath) except when travelling on the road (without enough water, or just passing through a mosque)” [an-Nisa’ 4:43]. If he is married, he has to avoid intimacy with his wife until he goes back to Makkah and does tawaaf al-ifaadah. End quote.
Majmoo‘ Fataawa Ibn ‘Uthaymeen (22/363, 364)
Based on that, your friend is still in a state of ihram for the ‘umrah for which he did tawaaf when he was junub. Therefore he has to avoid the actions that are prohibited when in ihram, and go to Makkah and do tawaaf and sa‘i, and cut his hair or shave his head. Thus he will have completed his ‘umrah and exited the ihram thereof.
And Allah knows best.