Hi there - I comment here based on memory and things change, however if your son was with you in Canada then it's likely that he was also the subject of a removal order because that's how Canada lawfully removes people.I have one question . I had applied asylum with my Son . But my case was refused . My son is 11 yrs Old . He is studying in 6 th class . if my son want to study in Canada after 12th class . It is possible ?. Can he apply the study visa to Canada for Higher study ?
If this is the case then the type of removal order makes a difference - Exclusion, Deportation or a Departure Order (these can be deemed to be a Deportation Order if you don't leave within a specific time period). So, he might need an ARC - Authorization to Return to Canada. https://www.canada.ca/en/immigration-refugees-citizenship/services/immigrate-canada/inadmissibility/reasons/authorization-return-canada.html
It is possible for him to study in Canada one fine day. There is an adage in immigration that when someone adds complexities to their immigration case file, it's time for a lawyer.
If you want technicalities, you've come to the right place so good luck.