Your divorced?Separated?Even if you have full custody you still need her to sign off on forms stating that she gives up all rights,and you need a court order stating that she is allowing this.
It does not mater if you have full custody or not.To remove children from acountry where the other parent lives you still must get the signatures of the other spouse.
People make this mistake,full custody does not give you total rights to do what you like,it just gives you care and control.The other parent still have rights to the children.
First you must have a judge approve the sign off form your wife then you need to get the immigration form http://www.canadainternational.gc.ca/iran/assets/pdfs/visas/30_1_eng.pdf this will give you the form your wife needs to fill out and get notorized.