I am a married Muslim woman and I work as a university professor in a non-Muslim country. When I first started my teaching career, I was surprised to find the students objecting to my hijab and making noise to prevent me from practicing my job. In addition, they would make ridiculous comments and create trouble in class.
Should I continue wearing the hijab or it is permissible to take it off to avoid problems?

Hijab is an individual duty upon the adult Muslim woman. God the Almighty says,
“And tell the believing women to reduce [some] of their vision and guard their private parts and not expose their adornment except that which [necessarily] appears thereof and to wrap [a portion of] their headcovers over their chests.” [Al-Nur: 31]

‘A`isha [may Allah be pleased with her] reported that when Asmaa` the daughter of Abu Bakr approached the Prophet [peace and blessings be upon him] wearing transparent clothes, he turned away from her and said, ‘O, Asmaa`! When a woman reaches the age of menstruation, nothing should be seen of her body except this and this,’ and he pointed to his face and hands” [recorded by Abu Dawud, Al-Bayhaqi, and Al-Tabarani].

If the case is as mentioned, it is impermissible for a woman to take off the hijab and uncover the body parts it covers before a non-mahram (a person with whom marriage is permissible) except when there is a necessity or a need that reaches the degree of a necessity. Examples include removing the hijab to undergo treatment and give testimony. This is because necessity makes the unlawful lawful and a need, whether general or personal, is treated as a necessity.[1]

Al-Shatibi wrote in Al-Muwafaqat, “The number of necessities are five. [They are]: preserving religion, life, progeny, property and intellect. Scholars agree that these five necessities are protected by all revealed religions. Purposes at the level of needs refer to those things that a person lacks but needs to bring him ease and comfort and alleviate hardships. If needs are not fulfilled, those accountable before the Law suffer hardship though these do not reach the level of expected common harm in public interests.”

Concerning the case in question, if the matter is restricted to only some disturbances from your students which you can overcome with tact, courteousness, and a proper handling of the situation, it is impermissible to for you take of the hijab. Otherwise, if matters escalate to assaults which cannot be averted or to losing your job when you cannot find another source of income except in this particular place, it is permissible to remove your hijab in the most restricted manner and for the least possible time while covering as much as possible from your body. This is based on the Islamic maxim that states, “Necessity is measured by its extent.”
God the Almighty knows best.
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[1] Al-Suyuti. Al-Ashabah wal Nadha`ir, pp.85-8.