The 1999 Constitution

Section 29 (1)

Any citizen of Nigeria of full age who wishes to renounce his Nigerian citizenship shall make a declaration in the prescribed manner for the renunciation. 

(In essence, an adult Nigerian can cancel their citizenship by making the appropriate declaration in the proper manner)

Section 29 (2)

The President shall cause the declaration made under subsection (1) of this section to be registered and upon such registration, the person who made the declaration shall cease to be a citizen of Nigeria. 

(The president will order the declaration to be registered and once that is done, the person ceases to be a citizen of Nigeria.)

Section 29 (3)

The President may withhold the registration of any declaration made under subsection (1) of this section if- 

(Notwithstanding the above, the president can stop the registration of the declaration if)

Section 29 (3) (a)

the declaration is made during any war in which Nigeria is physically involved; or 

(the declaration was made during a war that Nigeria is currently fighting or)

Section 29 (3) (b)

in his opinion, it is otherwise contrary to public policy. 

(If the president decides it is against public policy (this is entirely up to the president’s discretion)

Section 29 (4) (a)

For the purposes of subsection (1) of this section. 

“full age” means the age of eighteen years and above; 

(For the declaration to be valid, the person should be at least 18yrs old (which is the age of adulthood in Nigeria.)

Section 29 (4) (b)

any woman who is married shall be deemed to be of full age. 

(Every married woman is deemed to be an adult i.e. at least 18years old.)

Section 30 (1)

The President may deprive a person, other than a person who is a citizen of Nigeria by birth or by registration, of his citizenship, if he is satisfied that such a person has, within a period of seven years after becoming naturalised, been sentenced to imprisonment for a term of not less than three years. 

(Notwithstanding the above, a person, who is not a citizen by birth or by registration, can have their citizenship taken away if the person has been imprisoned for a time not less than 3 years in the 7-year period immediately following the naturalization of such a person. (take note that this is not absolute)

Section 30 (2)

The President shall deprive a person, other than a person who is citizen of Nigeria by birth, of his citizenship, if he is satisfied from the records of proceedings of a court of law or other tribunal or after due inquiry in accordance with regulations made by him, that – 

(A person who is not a natural born Nigerian can have his citizenship taken away if, after a court of law or tribunal or a panel of inquiry according to law has determined that the person has)

Section 30 (2) (a)

the person has shown himself by act or speech to be disloyal towards the Federal Republic of Nigeria; or 

(shown himself to be action or words, to be disloyal to Nigeria so basically treason or)

Section 30 (2) (b)

the person has, during any war in which Nigeria was engaged, unlawfully traded with the enemy or been engaged in or associated with any business that was in the opinion of the president carried on in such a manner as to assist the enemy of Nigeria in that war, or unlawfully communicated with such enemy to the detriment of or with intent to cause damage to the interest of Nigeria. 

(If during a war that Nigeria is a participant, the person is actively helping the enemy or was doing things calculated to help the enemy to the disadvantage of Nigeria. For instance, a naturalized Nigerian is convicted for aiding Boko Haram will have his citizenship revoked.)

Section 1-3 of the 1999 Constitution