can an employer take your job away from you after 16 years because you you do not have the degree or certiciate

Assuming that you do not have an employment contract which limits the reasons why you can be fired, or provides for procedural protections if your employer wants to fire you (e.g. requires a termination hearing, or that an arbitrator finds that there was good cause to terminate your employment, etc.), the answer is probably yes.  In most states, employees are employed "at will", meaning that they can be fired at any time for any reason, unless he or she has a contract (sometimes this contract can be created by an employee handbook) which says otherwise, or there is a statute which prohibits it (such as statutes which prohibit discrimination in employment based on race or gender, or which protects whistleblowers).