He migrated to a Muslim country, then he realised that the education system is not good; can he go back to complete his studies?
The ruling on migrating from kaafir countries varies according to a person’s situation, his ability to migrate and his ability to practice his religion openly there.
Hijrah is obligatory for one who is not able to practice his religion openly and is able to migrate.
But if a person is able to practice his religion openly, it is mustahabb for him to migrate (Hijrah) but is not obligatory. If a person is unable to migrate, he is excused by Allah, may He be exalted.
Ibn Qudaamah (may Allah have mercy on him) said:
With regard to Hijrah, people fall into three categories:
Those for whom Hijrah is obligatory: this applies to the one who is able to do it and is not able to practice his religion openly or establish the obligatory duties of his religion if he stays among the kuffaar. In this case, it is obligatory to migrate because Allah says (interpretation of the meaning):
“Verily, as for those whom the angels take (in death) while they are wronging themselves (as they stayed among the disbelievers even though emigration was obligatory for them), they (angels) say (to them): ‘In what (condition) were you?’ They reply: ‘We were weak and oppressed on the earth.’ They (angels) say: ‘Was not the earth of Allaah spacious enough for you to emigrate therein?’ Such men will find their abode in Hell — what an evil destination!”
This is a stern warning which indicates that it is obligatory. Establishing the obligatory duties of Islam is obligatory for the one who is able to do that, and Hijrah is necessary for fulfilment of that obligation; whatever is essential to fulfilment of an obligation is also obligatory.
Those for whom hijrah is not obligatory. This applies to the one who is not able to do it, either because of sickness, or because he is forced to stay, or because of weakness in the case of women, children and so on. In this case Hijrah is not obligatory, because Allah says (interpretation of the meaning):
“Except the weak ones among men, women and children who cannot devise a plan, nor are they able to direct their way.
99. These are they whom Allaah is likely to forgive them, and Allaah is Ever Oft-Pardoning, Oft-Forgiving”
And it is not mustahabb for them, because it is not possible for them.
Those for whom it is mustahabb but is not obligatory. This applies to the one who is able to do it, but he is able to practice his religion openly and establish it in the kaafir country. So it is mustahabb for him, so that he would be able to engage in jihad against them, increase the numbers of Muslims, and support them, and so that he can stop increasing the numbers of kuffaar, mixing with them and seeing evil among them. But it is not obligatory for him, because it is possible for him to establish the obligatory duties of his religion without migrating.
End quote from al-Mughni, 9/236
Based on that, if you are able to practice your religion openly as you say, then Hijrah is not obligatory for you, but moving to one of the Muslim countries is better and more safe, so as to avoid increasing the numbers of kuffaar, mixing with them and witnessing their evils, and so as to move away from fitan (turmoils, temptations) and causes of deviation which are prevalent in those societies, as well as for the sake of the children who are born to the Muslims there, to save them from being lost and going astray in Western societies. This applies in general, but a person may be in a place in those countries where he lives among a Muslim majority and is able to play his role in da‘wah, teaching and explaining Islam to others, in which case it is better to him to stay and not migrate.
So you should weigh up the pros and cons, and give priority to preservation of religious commitment over other interests, for religious commitment is the capital of the individual which must not be squandered.
With regard to going back -- temporarily -- in order to obtain a better education, we hope that there is nothing wrong with you doing that, especially if it is an education that you need or there is some benefit to the Muslims in it, but you should keep trying to find an opportunity to settle permanently in a Muslim country.
We ask Allah to guide and help us and you.
And Allah knows best.