Can I have my kids father's rights taken from him since he has not been in any kind of contacted them for at least 6 years?

First no, only the court can terminate parental rights. You don't say whether you and the father were married or if he is on their birth certificates. If neither one is the case, he has no rights because he is not their legal father. Has he been ordered to pay child support. To give you any meaningful information, an attorney would have to know a lot more than you've said.