Abducted students - now reunited with their families - said they were told to spread the message to other schools in the troubled English-speaking region.
Children kidnapped by gunmen in Cameroon said their captors had warned them not to go back to school.
They recounted their ordeal as parents packed up belongings from a boarding school now being shut down.
Kidnappers freed almost 80 school children and a driver in Cameroon's North-West region this week but kept hold of a principal and one teacher - two days after snatching them in a raid on the Presbyterian Secondary School.
The armed men had seized the kids on Monday in Bamenda - a green city nestled in the hills and hub of the country's troubled English-speaking region.
The military and a priest involved in negotiations blamed the abduction on anglophone separatists but a spokesman for the separatists denied this.
"It was around 3 in the morning. We were still sleeping, then we heard people shouting, some other people, some men, came and broke our door," a 13-year-old boy told Reuters TV.
Still in captivity
Early reports said all 79 kidnapped students had been freed. But CNN quotes school authorities as saying two boys are still held along with the two adults.
"They told us: 'come out'. They were all dressed in black."
Stopping children going to school is a favoured tactic of anglophone separatists, who say schools are being used to spread government propaganda.
"When they set us free, they said we should tell the other schools that they should stop, so no one goes to school," said the schoolboy.
The secessionists have imposed curfews and closed schools as part of their protest against Biya's French-speaking government and its perceived marginalisation of the English-speaking minority. The government has denied discriminating against them.
"I am really, really worried," a mother of one of the children said, before packing her boy's things into a car.
"I know his education is not guaranteed because of the security (situation) ... because I am not sure for his safety."